Bestiary: Oklahoma Land Crab

Because of who I am as a person, the following has been greeting me every morning since September: 

On a regular basis, I look over at it and think, for a second, that it says “Oklahoma Land Crab". For whatever reason, this week I was struck by inspiration and decided I needed to make that into a D&D monster. Though I suppose it wouldn't actually be from Oklahoma. So here are some points from the above document that would have to be covered in said monster:

• It's a crab that lives primarily on land.
• It has some connection to unethical land grabs.
• ... “such as the ‘borrowing' of ‘family members'..."
• “A man might swear that he had on his property a house ‘twelve by fourteen', though the measurement was in inches -- not feet, as he had allowed it to be assumed."
• “Observers also frequently noticed one glass window, unattached..."

A few notes first:

• I will add game stats in a separate entry later.
• Apparently the correct collective noun for a group of crabs is a “cast", so I've used it here.
• I'm making an attempt to give this a range of usefulness, because I think it works; so you can use this as:
• Stage One: A curiosity
• Stage Two: An annoyance
• Stage Three: A minor threat
• Stage Four: A mid-level threat
• Stage Five: A major threat
• Stage Six: A danger to the kingdom
• Stage Seven: A danger to the world

Land Crab

Also called the Civilized Crab, the Potemkin Crab, or Chousemann's Crab.

By Filo gèn'
Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=61489500

At its base, the Land Crab is just a sort of mildly magical vermin with some interesting mating behavior. The basic type of Land Crab will find a dark, somewhat damp, hopefully sheltered area -- possibly under a bush or similar -- and dig a burrow. When its burrow is prepared, it engages in its mating display: the crab will decorate the exterior of its burrow with wattle-and-daub huts built to crab-scale. Since these huts are purely decorative, not functional, and the crab is just a crab, they tend to be rather architecturally suspect: huts with seven windows and no doors, that sort of thing. Eventually, this display will attract a crab of the opposite sex.

Land crabs are social animals, and once a cast of crabs is properly established, one may find entire pseudo-villages of questionably-designed, crab-scale huts, linked to a system of burrows occupied by an extended family group. This is considered a Stage One cast of Land Crabs; as the population of this cast grows, eventually eggs laid by this cast will hatch into unusual, specialized types, which indicates a transition into Stage Two. It should be noted that early-Stage-Two casts of land crabs are occasionally kept in large terraria by wealthy eccentrics, much like an elaborate ant farm. More than one disaster has resulted from one of said eccentrics failing to properly maintain their terrarium and allowing the cast to grow & progress more than it should.

By Andrea Westmoreland from DeLand, United States
Fiddler Crabs at Indian River Lagoon, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=26015998

In a Stage Two cast, crabs of any of the following types may be born:

• Vulgaris -- the basic type of Land Crab. As far as game statistics go, the Vulgaris is identical to a standard-issue crab, though they do tend to swarm.
• Ignis -- capable of generating intense heat from their claws. This can cause 1 damage in combat, but is more likely to be used to create metal and glass additions to the decorative huts.
• Acidus -- spits acid up to 5 ft. This can cause 1 damage in combat, but is more likely to be used to burrow into or shape stone.

Though in a Stage One cast, member crabs are content to lay their eggs in any puddle or other damp place in which the semi-aquatic larvae can mature, members of a Stage Two cast will deliberately seek out artificial bodies of fresh water, preferably drinking water. Wells are strongly preferred, and casts with a sizable number of Acidus will often begin extending their burrows into and through the stone walls of wells for this purpose. The overarching goal of this behavior is to cause local humanoids to ingest Land Crab larvae; larvae within a living body will adopt parasitic behavior and mature into a Vavato. Once this has been achieved with a sapient humanoid, the colony is considered to be in Stage Three.

By © Hans Hillewaert
CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=26106449

Vavato

These are specialized parasitic types of Land Crab, created when Land Crab larvae are ingested by a living being. (The host gets a Fortitude save DC 15 to resist infection.) Once they have matured, they begin altering the thoughts and behavior of the host body. The host will gradually become obsessed with constructing buildings on their own scale with the same erratic pseudo-architecture as the minature versions built by the Land Crab. In time, as the parasite grows more dominant, the host will begin considering themselves part of the Land Crab's cast, and will defend it if necessary. Sapient beings will lose the capacity for language as the infection advances; they descend to speaking in word salad, then pure gibberish. Sapient beings will also try to spread the infection throughout their village or community until the infected are a majority. The infected can survive for a long period of time, but after the first year or two, their brain accumulates enough stress that they become no more intelligent than crabs. As they inhabit the host, the Vavato will gradually collect bits of knowledge or memory from the host's degrading brain matter. This knowledge will be passed on to the Vavato's spawn; once the host dies, the Vavato's behavior shifts to producing as many eggs as possible, which will hatch into simple Vulgaris, leave the corpse, and rejoin the main cast.

Stage Three casts are those that have successfully parasitized sapient humanoids. At this point, they will focus on expanding a pseudo-village at human scale. They will also begin to access their hereditary memory -- an accumulated pile of knowledge passed down from previous generations of Land Crabs in a fragmentary and disorganized fashion. Though said hereditary memory is the result of untold numbers of Vavato collecting memories from similarly-untold numbers of hosts, the crabs have to deal with not only a certain amount of copy degradation, but also with the fact that they are crabs with tiny crab brains and don't actually understand most of it. As a result, their attempts to make a more detailed, realistic humanoid village tend to go wrong. Perhaps they understand the concept of a forge, but not that it goes only in specialized buildings; or they recognize that meat and vegetables are often kept within humanoid habitations, but missed the information that they're supposed to be preserved and stored, not just left laying around.

By Timquade at English Wikipedia
CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=7037008

In a Stage Three cast, crabs of any of the following types (in addition to those from Stage Two) might be born:

• Magus -- crabs who have the hereditary memories of parasitized spellcasters. When threatened, they will cast spells. Of course, once again, they are crabs with tiny crab brains, so the GM is encouraged to create a random spell table to determine what they cast in any given situation.
• Scriba -- crabs tasked with creating signage and decoration. Any images they create tend to be kind of strange, as it's all done through confused instinct. Their signs also tend to be incomprehensible word salad; the only consistent feature is that said signs will reference an authority figure by the name of Chousemann. The creation of these signs and images is done by either carving the wood with their claws or “painting" with whatever substances happen to be available.
• Messor -- larger crabs, roughly the size of a housecat. These will leave the pseudo-village and gather resources, which they bring back. “Resources" could include anything from construction materials to food, both of which the crabs have a rather broad view of.
• Cogitatio -- crabs with a larger share of the hereditary memories and a degree of actual intelligence. Roll 1d12 for their Int score. Since they have no vocal apparatus, of course, they can't really communicate with anyone other than crabs unless they have some sort of Morse system on hand.
• Artifex -- crabs that produce crafted items. Usually, the Land Crabs don't create anything other than architecture and certain large furniture items, preferring simply to fill their pseudo-houses with stuff they find, but the Artifex crabs will actually try to create things. They tend to have a lot of technical skill, but again, poor understanding, so items they make are well-constructed but somewhat... off. Their crafting endeavors are aided by their access to the same abilities employed by the Ignis and Acidus crabs.

Stage Three can persist indefinitely, as building to the population required for Stage Four is diffcult. In order to maintain the parasitized-humanoid population necessary to keep building large-scale structures, a Stage Three cast may resort to breeding new generations of humanoids from the parasitized population, and/or kidnapping outsiders to add to their population.

By I, Ianare, CC BY 2.5, https://commons.wikimedia.org/w/index.php?curid=2438589

Samples of text by Scriba crabs
The clear star that is yesterday can by order of Lord Chousemann.
The person you were before owes allegiance to Queen Chousemann.
Courts of Chousemann see only sterile twilight.
Fragment of vistas by red in tower -- Chousemann
Opiate spaces and turmoil come and wafted him sleeping meads much, by order of Shire-Reeve Chousemann.
Merge with lotus blossums and have world one forever with Major General Chousemann.
It is written by St. Chousemann that whirlpools stared by sunrise.
Yet Chousemann is Employee-of-the-Week enough to a dim court when age fell upon to make him sleeping eye may never.

The Land Crabs transition to Stage Four once their pseudo-village reaches a certain size and population density. This stage is characterized by increased construction and defense. Crabs will focus on building stone walls and towers around their pseudo-village, eventually enclosing the entire settlement in a crude approximation of something like a castle. The following types of crab might be born (in addition to the types from previous stages, which will continue showing up):

• Structor -- crabs the size of horses. They are laborers, and focus entirely on the construction of stone walls and towers; they seem instinctively able to search out good stone, quarry it, carry it back to the pseudo-village, and cooperate on construction. 
• Custos -- slightly smaller than the Structor, tasked with patrolling the outer perimeter of the village. They naturally settle into shifts, so that at least one-third of the Custos in the cast are on guard at any given time. 
•  Ballistarius -- crabs of roughly the same size as the Custos who take up residence in the stone towers and throw heavy objects at intruders. Usually, the Ballistarius will simply hurl large stones, which they tend to collect for this purpose; however, in a pinch, they'll throw whatever happens to be available.
• Rutrum -- crabs of housecat-size who dig trenches or moats outside the walls. They may also work on expanding the burrows of the cast, resulting in vast underground warrens beneath the pseudo-village.
• Fulgens -- small crabs with glittering carapaces that resemble bits of precious stone or metal. They can hibernate for exceptional periods of time. They produce specialized drought-resistant eggs that can remain viable but unhatched until the Fulgens introduces them to a suitable environment.

By Alex Barabas
Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=15208992

Other new behaviors in Stage Four include the Artifex and Magus crabs cooperating. Perhaps one in a hundred items created by the Artifex is enchanted by the Magus. This is, however, simply instinctive behavior, so there is no rhyme or reason to what is enchanted with what spell and how it works. The Artifex will also sometimes dig out small socket-like holes in their crafted items, which the Fulgens will be encouraged to occupy. A Fulgens carrying a clutch of eggs will generally take up residence in the socket, then hibernate; parasitized humanoids will occasionally gather up these items and wander away from the cast, making attempts to trade, sell, or give the infested items to travelers. The Fulgens remain in hibernation within the items until they sense they are in a population center or near a source of fresh water, at which point they will awaken, scurry off, and seek out a damp place to hatch said eggs. In this manner, a new cast of Land Crabs may take root elsewhere.

Once their pseudo-castle is complete and the population has again increased to a certain density, the Land Crabs enter Stage Five. In this stage, they attempt to expand their population and access to resources through more aggressive means. The following new types of crab will begin to appear:

• Agricola -- similar in size and appearance to Vulgaris. Agricola crabs will spread out and try to cover the landscape around the pseudo-castle. Any plants that do not produce substantial amounts of food for the crabs or their human hosts will be attacked; the Agricola will then attempt to spread the seeds of more productive plants. Of course, their tiny crab brains can't get any more complicated than sorting plants into “good" and “bad", attacking the “bad", and burying seeds from the “good", so their agricultural efforts are erratic at best.
• Venator -- resemble Messor, but sleek, fast, and deadly. These crabs roam the area for miles around the pseudo-castle, attacking any non-humanoid animal larger than a cockroach and dragging the meat back to the castle to feed the growing cast. They are capable of basic pack-hunting tactics.
• Mercator -- one of the most deviant varieties of Land Crab, the Mercator attempts to masquerade as humanoid. It has one pair of hypertrophied legs and one pair of exceptionally dextrous claws; its other limbs are small and kept folded against its body, hidden from view. It is built to stand bipedally, and is proportioned so that it is long rather than wide. The resulting silhouette is something like a bulky, hunchbacked goblin. The Mercator will cover itself in found clothing, attempting to conceal its crustacean nature. It may also repurpose the skins of deceased humanoids into its disguise, exuding a preservative to keep the material from rotting. The Mercator can speak, with some difficulty due to imperfect vocal apparatus, is passably intelligent (roll 2d4 for its Int score), and is generally capable of speaking an approximation of the local language that is something like a crude trade pidgin. It will depart the cast with a large quantity of the Artifex's trade goods, and attempt to sell them or trade for other items of value. Once its supply of trade goods has been depleted, or if it has accumulated as much bounty as it can carry, it will return to drop off its acquired wealth, resupply, and begin another trip. Alternately, if the cast is in need, it may take some of the hoarded wealth to the nearest town and attempt to purchase supplies.
• Latro -- larger, sturdier versions of Venator. Latro crabs will travel in packs and conduct raiding operations on nearby humanoid settlements or travelling groups. Generally, they are not interested in killing the inhabitants, but will not hesitate to slay anyone who gets in the way and drag them back to the cast for food; they are instead here to gather supplies. Often, smaller varieties of Land Crab cling to Latro during these journeys so that they can spread around the area and lay eggs in the wells of the settlements Latro visits. Notably, no effort is made to coordinate between Latro and Mercator, so that settlements might be raided by the Latro one day, then find a Mercator showing up as if nothing had happened the next.
• Tesserarius -- The Tesserarius mature into a small, sessile, barnacle-like form rather than the mobile crab-like forms of the other types. A juvenile Tesserarius will seek out a position where they can best observe the pseudo-castle, then fasten itself to a sturdy surface with a powerful natural adhesive and begin to develop a thick, immobile shell. Tesserarius are one of the few sapient varieties of Land Crab -- Int 3d6 -- and will use their position to coordinate the defense of the cast. They can communicate with each other and with the non-sapient crabs through chemical signals; if weather conditions prevent this mode of communication over distances, the Cogitatio will be employed as messengers. A sizable population of Tesserarius will eventually result in a properly-constructed defensive wall and a much more organized guard.

By Beauregard Laura, U.S. Fish and Wildlife Service

Eventually, the cast will successfully infect nearby settlements, and will work towards speeding their development into other Stage Five casts. A group of Stage Five casts cooperating -- as they often do, if they are from the same genetic line -- constitutes a Stage Six cast.

In Stage Six, the Land Crabs effectively constitute a small nation -- despite the fact that only a handful of them are sapient by any measurement -- and will behave as such. Specifically, they begin to engage in conquest. A Stage Six caste will begin to add the following to its ranks, roughly half of which will remain at the pseudo-castle and half of which will go out to subjugate nearby regions:

• Venenum -- long, thin, fast-moving crustaceans about the size of a goat. They have a venomous bite.
• Poison: Land Crab Venom | Type: Injury | Fort DC: 17 | Onset: - | Frequency: 1/round for 6 rounds | Effect: 1 Int and Con damage | Cure: 2 saves
• Gigas -- thirty or more feet across, thick exoskeleton, terrifyingly strong. In addition to providing pure brute strength, the flat, rough shell of a Gigas is ideal for providing transport and support to smaller units, which often use the Gigas as a sort of mobile staging area.
• Morbus -- a small crab, resembling the Vulgaris but with more pronounced claws. The Morbus reproduce frequently, often laying eggs in any freshwater source that the other Land Crabs happen to pass, with the goal that they will have a clutch of fertilized eggs ready when they are in a combat situation. In combat, the Morbus will latch onto opponents and attempt to tear holes in their flesh in which to lay eggs, with the goal of creating more Vavato.
• Hastatus -- look something like four-foot-long shrimp with sharp spear-like appendages rather than claws. Used as infantry.
• Malleator -- similar to the Hastatus but with heavy, mineralized club-like appendages instead.
• Bucinator -- clacks its claws together with exceptional force, creating a sonic attack. The attack of a Bucinator deals 2d6 damage to anyone in a 30-ft cone.
• Sanguis -- small creatures an inch or two long that will latch onto opponents and burrow into them. Once they are too deep to be easily removed, they will drink their victim's blood until said victim dies; they secrete an anticoagulant to ensure this is the eventual outcome.
• Sagittarius -- fast-moving cat-sized crabs that, like the smaller Acidus, can spit acid. The Sagittarius, however, can reliably hit targets 30 ft. away, and does 2d6 damage with each volley.
• Alaris -- horse-sized and long-legged, with a spiny carapace and powerful claws. 
• Insidia -- lanky creatures like a five-foot-long stick insect. The Insidia are primarily used for defense of the cast, and remain hidden or camouflaged near the wall in case of intruders, in which case they rapidly impale them on their long, thin claws. A few will accompany the more traditional units in conquest behavior, sneaking around the edges of the battlefield and picking off stragglers. They also can spit chemical signals, allowing the communication of basic information about whichever enemies they are spitting on. One of their “signals" is just a bioluminescent liquid that they spit on any opponents trying to be sneaky.
• Dux -- visually unimpressive and liable to blend in with the other small crabs, the Dux is actually the most intelligent variety of Land Crab. Each “unit" of the Land Crab “army" has a single Dux strategizing and commanding. A Dux has 1d12+10 Intelligence, and communicates telepathically with all other Dux in the cast. It uses this same talent to direct the non-sapient crabs under its “command".
• Legatus -- the Legatus resemble Vulgaris in all respects except for their exceptionally polished-looking exoskeletons, which resemble smooth mother-of-pearl. At some point after the Land Crabs have begun their hostilities, a handful of Legatus will be escorted -- by one of the larger, faster types of crab -- to something in the area that looks like a seat of governmental authority. (The Land Crabs only know the most superficial aspects of humanoid government, so there's some guesswork involved.) Once there, the Legatus will begin demanding concessions and/or surrender from their humanoid “enemies", and try to initiate talks with humanoid diplomats. Thanks to an inborn magic, the Legatus are able to generate speech despite a total lack of appropriate apparatus -- it's much like a magic mouth spell. Their speech is always eloquent, calm, and in an accent or dialect that strikes the listeners as being slightly foreign, but highly cultured and intelligent. Talks inevitably stall, as the Legatus speak in circles, never quite settle on anything, and often say that they'll have to consult with their Queen on the issues. There is, of course, no Queen -- despite appearances, the Land Crabs are not fully eusocial -- and the Legatus do not have the authority, desire, or capacity to make any diplomatic agreements. A Legatus has an Int score of 1d4+2, and nearly all of their brainpower is taken up with running what is essentially an arcane ELIZA program that generates the Legatus's “speech". Everything the Legatus says is completely meaningless; it's just following inborn directives and trying to make sure that its words sound like believable responses to the conversation. The apparent purpose of the Legatus is to confuse and frustrate the humanoids who might otherwise deal with the problem better; it also will try and find a chance to lay eggs in the water supply once it's established in its new diplomatic position.

By Thomas Brown - Land Crab (Gecarcinus ruricola)
Uploaded by mgiganteus, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=27451076

At this point, the Land Crabs will continue expanding their territory until stopped. If, at any point, a significant period of time (a few years) passes where they own a large (kingdom-sized) piece of territory and are consistently prevented from expanding their borders, they may enter Stage Seven. 

Stage Seven is much like Stage Six, but the crabs get serious about reaching new territory. They begin trying to traverse significant geographical barriers that may have previously slowed them, such as mountains or oceans. This is accomplished by use of the two new varieties of crab that the cast will produce in Stage Seven:

• Colossus -- the Colossus is several stories high, with long, sturdy legs. It is used as a sort of vehicle by other Land Crabs to get past borders both natural and artificial. 
• Cetus -- resembles an enormous marine crab. Its shell is mostly hollow, though, serving as a place for other Land Crabs to ride inside of. This is the means by which Land Crabs may move from one landmass to another. The Cetus travels relatively close to the surface of the water, so that it can regularly take in fresh air for its passengers. It may also surface to let them attack passing ships -- said attacks are usually brief and largely for the purposes of gathering food, but also distract from a few Vulgaris slipping on board so that later they can find the ship's water supply and lay eggs in it, thus potentially sending a ship full of parasitized humans into a nearby port.

Popular Science Magazine, June 1920