Bestiary: Laantaug

Far, far below the deepest delvings of the Dwarves, the world is gnawed by nameless things.
-- J.R.R. Tolkien, The Two Towers 

I'm dreaming again / Of life underground / It doesn't ever move / It doesn't make a sound.
-- Oingo Boingo, “Just Another Day"

This is an entry designed to answer one of those strange, niggling questions that arise in your standard D&D setting -- specifically, what supports the Underdark ecosystem? This comes up whenever people start asking too many questions about the vast subterranean world that is often assumed in D&D settings -- since, you know, the drow, duergar, grimlocks, troglodytes, &c. need a place to live. (Patrick Stuart, who wrote a whole book about the underground world in D&D, posted a relevant item.)

The whole debate tends to go something like this:

So these huge cities of drow, what do they eat?

Oh, they raise herds of these animals called rothé -- kind of like underground cattle.

Cool, cool; so what do the rothé eat?

Cave fungus.

Right, but cattle eat a lot. Raising herds of bovines is a tremendously energy-inefficient proposition; even using calorie-dense feed, you still need something like ten pounds of matter for every one pound of beef you produce... is there really that much fungus?

Yes. So much fungus. The Underdark is packed with all kinds of fungus.

So what does the fungus feed on? It still needs to get energy from somewhere.

More fungus, okay? It's fungus all the way down.

That makes no sense. Energy doesn't appear from nowhere; up on the surface, everything comes back to getting energy from the sun, but there's no solar radiation down here...

Fine, it's friggin' magic radiation or something.

It's what?

The drow priestess stabs you in the face.

Anyway, I'm designing something that can at least partially address this issue. This might turn into something of a series, addressing some of the oddities of the D&D world -- I already have an idea for a creature that explains those huge, anachronistic sewer systems you sometimes find in otherwise-medieval-European towns.¹

This particular creature was inspired by a video of chemosynthetic communities taken by the Okeanos Explorer last month. I looked into these sea-floor ecosystems and borrowed a number of ideas: the chemosynthesis of giant tube worms, the ecological value of a whale fall, the extreme sexual dimorphism of the anglerfish, and the body plan of a sea cucumber. All of this gives us the:

Laantaug

“Laantaug" is, according to current linguistic theories, a corruption of an Aklo compound meaning “smoke worm".² This is, technically, speaking, a misnomer -- the vapors that characterize a laantaug ecosystem are not actually smoke, but a chemical soup that emerges from the burrows of the male laantaug.³ Said vapors are the only evidence most subterranean peoples ever see of the laantaugs' existence; one would have to enter the poisonous vapor in order to see the laantaug females, and the laantaug males typically burrow deep, far from population centers. The latter, however, are occasionally encountered by unlucky explorers.

A male laantaug is vaguely serpentine -- imagine a sea cucumber, enlarged until it's five or six feet long, and thick enough that, if you were to hug it for some reason (don't), you would just barely be able to touch your hands together behind it.

Here's a fun reference image if you need one.
Illustration by Charles Frederick Holder, in Along the Florida Reef, published 1892.
 Retrieved from the Freshwater and Marine Image Bank, University of Washington.

The male laantaug is deceptively fast, pulling itself along on dozens of tentacle-like feet, and dangerous to the unprepared. Thankfully, one rarely encounters them by accident -- they spend the majority of their adult lives creating and tending their burrows, and you'll only see them if their burrow accidentally intersects a tunnel you're trying to traverse. If you do encounter one, however, you will not only have to deal with the dangerous contents of their burrows -- which are essentially mini-ecosystems completely hostile to humanoid life -- but with their ability to re-purpose their burrowing capabilities for self-defense. They burrow by means of acidic secretions, and will respond to any threat by spitting acid at it or, if in close quarters, wrapping themselves around it and letting their skin's coating of acidic substances do the work. Their thick layers of rubbery skin and alarming strength make them difficult opponents if you don't know what you're getting into. They are also completely unbothered by fighting in the darkness -- laantaugs are eyeless, and rely on their other senses to interact with their environment.

Here's another fun reference image -- its mouth is against the sand here.
Thelenota ananas  |  Photo by David Burdick -- NOAA Photo Library

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Laantaug stats (male)

CR 7; XP 3200
Medium Animal
Init +2; Senses Tremorsense 30ft., Blindsight 30ft; Perception +14

Defense

AC 21, touch 12, flat-footed 19 (+2 Dex, +9 natural)
hp 95 (9d8+54)
Fort +12, Ref +8, Will +5
Immunities: Acid

Offense

Speed: 30 ft., climb 30 ft., burrow 30 ft.
Melee Attack: bite +10 (1d6+4)
Ranged Attack: acid cpit +8 (3d6)
Special Attacks: Constrict (1d6 +4d6 acid +4)

Statistics

Str 18, Dex 14, Con 22, Int 2, Wis 14, Cha 10
Base Atk +6; CMB +10; CMD 22
Feats: Greater Grapple, Improved Grapple, Improved Natural Armor, Lunge
Skills: Perception +14
Special Qualities: Tremorsense 30ft, Blindsight 30ft

Special Abilities

Constrict (Ex): A laantaug can crush an opponent, dealing 1d6+4 bludgeoning damage and 4d6 acid damage, when it makes a successful grapple check (in addition to any other effects caused by a successful check, including additional damage).
Acid Spit (Ex): A laantaug can spit acid up to 60 feet as a ranged touch attack. This attack causes 3d6 damage; using it is a standard action.
Deleterious Bite (Ex): Anyone bitten by a laantaug must make a Fortitude save DC 20 or be nauseated for 7 rounds.

Ecology

Environment: Subterranean
Organization: Solitary or Cluster (1-12 females, 12-144 males)
Treasure: I guess you could harvest the acid, or some rare fungi.

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The female laantaug is a different story. It's virtually impossible to encounter one by accident, as they spend their adult lives largely sessile, moving only to ensure continued access to the burrows the males produce. The chemical soup said burrows emit makes the area in which a laantaug cluster is located extremely difficult to traverse; the air is extremely toxic, and navigation is made difficult by the thick, opaque billows of dark-yellowish vapor that characterize these clusters. So, generally, if you're getting near a place where female laantaugs might be found, you know about it well before you actually run into one.

The female laantaug also secretes acid, but does not exactly burrow with it, just hollows out a living space. Female laantaugs grow continuously over the course of their life, and are truly massive by the time they reach adulthood.

Imagine that those things around it are trees. That size.
Giant california sea cucumber; image from NOAA.

Their acidic secretions mean that the cavern in which they have settled grows with them; if they become large enough to press uncomfortably against the sides or the roof of the cavern, they simply dissolve the stone until they are comfortable again. In this manner, it is theoretically possible for a laantaug cluster to intersect with another inhabited space underground, but it's rare -- which is good, because the scale of such an event and the toxicity of the vapors involved makes it less like a monster encounter and more like a natural disaster -- think limnic eruptions but with a bonus of giant acid-spitting worms flailing about in confused aggression.

Accidentally breaking through into a laantaug cluster is also a serious mining hazard, to be avoided not just because of the danger, but because of the embarrassment. Delving too greedily & too deep and awakening a balrog is one thing; delving too greedily & too deep and being killed by toxic worm smoke is not something you want mentioned in your epitaph.

Old illustrations of sea cucumbers are unexpectedly delightful.
F. Huth -- Report on the scientific results of the voyage of H.M.S. Challenger during the years 1873-76

In the normal course of their life, female laantaugs remain in their caverns, only moving when necessary, increasing the size of their cluster, growing over the course of centuries to truly geologic proportions, until an illness or similar manages to kill them off. (They are biologically immortal, and don't die of old age; they just keep getting bigger.) They are able to defend themselves from anything that manages to brave the noxious haze of their cavern, though; though they can't spit acid, they can smack predators around with their tentacles pretty well, or just gradually steamroll over them.

And then you'd get this view.
Illustration by Alfred William Alcock in Naturalist in Indian Seas, published 1902.
Retrieved from the Freshwater and Marine Image Bank, University of Washington.

As a bonus, the cavern in which a cluster of laantaugs makes its home gradually also becomes home to exotic extremophile varieties of bacteria and fungi. A female laantaug provides a large and stable biomass, and is often extensively colonized by symbiotic or parasitic organisms; direct contact with one, unless you've somehow managed to develop an immunity to diseases that aren't really found anywhere else, is usually not healthy.

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Laantaug stats (female)

CR 10; XP 9600
Colossal Animal
Init -4; Senses Low-Light Vision, Tremorsense 30ft, Blindsight 30ft; Perception +25

Defense

AC 30, touch -2, flat-footed 30 (-8 size, -4 Dex, +32 natural)
hp 176 (13d8+117)
Fort +17, Ref +4, Will +13
Defensive Abilities Half Damage from Weapons
Immunities Acid

Offense

Speed 5 ft.
Melee: 2 tentacles +3 (3d6+2 plus disease)
Space 40 ft.; Reach 40 ft.
Special Attacks: Engulf (DC 18, 1d8 acid plus disease), Disease (Ex) (injury, save DC 25, onset 1d3 days, frequency 1 day, effect 1d6 Con damage, cure 2 consecutive saves)

Statistics

Str 15, Dex 2, Con 28, Int 3, Wis 28, Cha 10
Base Atk +9; CMB +19; CMD 25
Skills: Perception +25
SQ Animal Traits, Blindsight 30ft

Special Abilities

Engulf (Ex): A laantaug can engulf creatures in its path as part of a standard action. It cannot make other attacks during a round in which it engulfs. The creature merely has to move over its opponents, affecting as many as it can cover. Targeted creatures can make attacks of opportunity against the creature, but if they do so, they are not entitled to a saving throw against the engulf attack. Those who do not attempt attacks of opportunity can attempt a DC 18 Reflex save to avoid being engulfed; on a success, they are pushed back or aside (target's choice) as the creature moves forward. Engulfed opponents gain the pinned condition, are in danger of suffocating, are trapped within the creature's body until they are no longer pinned, and are subject to 1d8 acid damage plus disease each round. The save DC is Strength-based.
Disease Attack (Ex): A laantaug causes disease in those it contacts.  A laantaug's disease has a fortitude save DC of 25, an onset of 1d3 days, a frequency of 1 day, causes 1d6 con damage, and takes two consecutive saves to cure. The save DC is constitution-based.

Ecology

Environment: Subterranean
Organization: Cluster (1-12 females, 12-144 males)
Treasure: Standard amounts, but entirely composed of gems, unrefined metals, and  gear of others who stumbled into this area.

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So now the fun part -- the ecology section. (I know that sounds sarcastic, but you have to admit that the ecology of D&D monsters really is often the fun part.) Disclaimer going in: I'm in English Linguistics, not any sort of life sciences, so don't expect this to be scientifically plausible to any degree. All of my bio knowledge is based on high school courses and a habit of falling into Wikipedia rabbitholes. So just fill in any bits of severe implausibility with “magic" or “specialized microorganisms".

Also, I'm going to keep putting old drawings of sea cucumbers here.
From Description de l'Égypte : ou, Recueil des observations et des recherches qui ont été faites en Égypte
pendant l'expédition de l'armée française. Accessed through the New York Public Library's Digital Library.

The life cycle of a laantaug starts with an egg, hatching in the toxic vapors of a laantaug cluster. The laantaug larva, one of hundreds hatched in its clutch, is immediately thrown into intense competition with its fellows. Not yet having developed the chemosynthesizing ability of an adult laantaug, they have to survive by grazing on the extremophile fungus that grows in the cluster, and they also have to dodge predation by the few other animals that can survive in this environment. The first year or so of its life is spent like this, growing large enough that it can venture out of the cluster -- at this time, it is roughly the size of a field mouse.

They look something like this.
Illustration by Ernst Haeckel in Kunstformen der Natur, published 1904.

By this point in the laantaug's life, it has had enough time to build up a significant internal colony of the symbiotic bacteria that are essential to the adult laantaug's feeding process. The laantaug does not have these bacteria at birth; its time in the cluster ensures that it is exposed to them on a regular basis, and eventually acquires a symbiotic “infection" that takes up residence in its digestive system. The bacteria convert various gases and chemicals that have accumulated in pockets within the rock into organic molecules from which the laantaug can extract nutrition. The laantaug exhales excess gases and unusable compounds in the form of a dark yellowish vapor, which is why it was called the “smoke worm". Said vapor smells vile, and is both toxic and flammable -- some of the gases the laantaug seeks out are methane and various sulfides.

From Treasures of the Deep: a Descriptive Account of the Great Fisheries and Their Products, published 1876.

Juvenile laantaugs may remain in the same cluster where they were born, provided that the cavern in which the cluster is located has the resources to sustain them. If the chemicals available in the region aren't enough to sustain additional laantaugs, they will seek out a place where said chemicals are available and start a new cluster. The male juveniles, who are much more numerous, will mature and begin to construct burrows once they find such a place -- these will gradually become deep, labyrinthine systems of tunnels carved out as the laantaug searches for the chemical deposits they require. Odds are good that the laantaug has inadvertently carried some spores over from the cluster where they were born, so that the aforementioned extremophile fungus will begin to line the walls of their burrow -- which is fine, as it can function as an emergency food service when needed.⁴

I looked up the original source of this image to get the citation right, and the Google Translate version produced the following sentence: “They wish to learn from us more about the synapses that the anchor used long before the invention of navigation, and about the Chirodians, who set thousands of crystal locomotive wheels in motion at once." I have no clue what it's trying to say there, but the Lost Civilization of the Chirodians might be a future entry.
(I did figure out that “Chirodian" was supposed to be “Chiridota".)
From “Freuden der Mikroskopie" in Die Gartenlaube.

At the opening of a laantaug's burrow, a conical structure of partially-dissolved stone (which will gradually dry and solidify again) gradually develops, consisting of the material that they have had to excavate from their burrow. Explorers in the subterranean realm sometimes refer to these as “worm chimneys", and it's not uncommon for someone to come up with a harebrained scheme to brave the toxic vapors and access these chimneys -- in addition to the mundane stone, the chimneys contain any chunks of material that the laantaug found difficult to dissolve and just shoved out of the burrow whole -- which could include gems or hard metal ores. There might also be nothing, but people have gotten rich off of these things before, and hope springs eternal.

They are not dissimilar in appearance to these “black smoker" vents.
By Rogers AD, Tyler PA, Connelly DP, Copley JT, James R, et al. in “The Discovery of New Deep-Sea
Hydrothermal Vent Communities in the Southern Ocean and Implications for Biogeography"

The worm chimneys constantly vent the sort of vapors that a laantaug needs to survive -- the male laantaug metabolizes what they need, then allows the rest to escape the top of the vent.⁵ The escaping vapor is meant to attract juvenile female laantaug, who will seek out one of these chimneys and settle down by it before maturing into its sessile adult form. Thus, a new cluster begins to form. The female laantaug feeds on the vapor coming out of the chimneys, and the strange little laantaug ecosystem begins to develop around her.

From Report on the scientific results of the voyage of H.M.S. Challenger during the years 1873-76

After the male laantaug reaches a certain point in its life -- it is unknown whether this is tied to age directly, or some other trigger -- then it will emerge from its burrow and, much like the anglerfish,⁶ enter into a direct symbiotic relationship with the female, eventually being absorbed almost entirely. This allows the female to essentially self-fertilize whenever there are sufficient resources for a new clutch of eggs. Ideally, by this point, several male laantaugs have established burrows in the area, so that there are plenty of resources available for the female and her eventual offspring even after one chimney stops producing. There may even be multiple females, if the region is sufficiently rich in resources.

By Alfred G. Mayer in Sea-Shore Life: the Invertebrates of the New York Coast and the Adjacent Coast Region, published 1906.

So that's the laantaug life cycle. As alluded to, however, there is an entire miniature ecosystem built around them. Fungus grows on and around the laantaug, and a handful of species of isopods and gastropods are able to survive the hostile environment well enough to feed on the fungus and laantaug larvae, or parasitize the female laantaug. Other, more conventional organisms prey on any animals that get close enough to the edge of the toxic region.

Here's a gastropod that lives near deep-sea hydrothermal vents.
Its shell and scales are partially composed of iron compounds.
I might have to give this guy his own entry.
By Kentaro Nakamura, Hiromi Watanabe, Junichi Miyazaki, et al. in “Discovery of New
Hydrothermal Activity and Chemosynthetic Fauna on the Central Indian Ridge at 18°–20°S".

The real impact, however, comes when a female laantaug dies. This could come to pass for any number of reasons -- the organisms parasitizing her could have gotten out of control, or the necessary chemicals in the region might be getting used up, or maybe there was a cave-in. When this happens, the other organisms in the laantaug ecosystem explode in population -- the amount of food represented by a dead creature of that size simply cannot be overstated. As the laantaug carcass is consumed, the isopods and gastropods that have so dramatically increased in population will start venturing far afield in search of food, and will provide a sudden boost in food for the predators that live outside the noxious haze of the chimneys, and so on.

Giant isopods are a pretty cool example of a scavenger that
would be thematically appropriate here. I think I've done enough
with crustaceans for now, though, so she'll have to wait a while.
Photo by Eric Kilby -- https://commons.wikimedia.org/w/index.php?curid=44436161

In the rare case that a laantaug cluster fails, and the chimneys stop producing vapors, the effect is magnified intensely -- not only is there more meat available for the scavengers, since the entire cluster has died, but it's accessible to more organisms. This event has such a dramatic impact on the ecosystem that sapient beings for miles around will notice the population of wild animals spiking... then, once the laantaug carcasses are finally consumed by fungus & scavengers, and the scavengers are eaten in their turn, nearby sapient beings will notice lots of hungry predators looking for a new food source.

So there's the laantaug. A sea cucumber the size of a village that creates ecosystems based around chemosynthesis, thus providing a much-needed infusion of energy and biomass into the Underdark. If I were more diligent about these things, I'd also tell you about the unusual properties of the fungus that grows in laantaug clusters and maybe make some kind of ruling about harvesting their acid, but I think this is plenty for now.

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1 Yes, yes, sewer technology is thousands of years old. If your world is based on the Roman Empire or the Indus Valley Civilization, sewers are reasonable. Medieval Europe was kind of short on sewers, however, and definitely didn't have the massive labyrinthine ones that sometimes crop up in D&D games. Now, back on track, please.^↩

2 Why, yes, I am making notes for a possible Aklo language post in the future. I'm currently trying to decide whether Aklo or Goblin would be the better choice for the next entry in that particular series. If you have thoughts or other requests, do let me know.^↩

3 Come to that, they're not really worms, either.↩

4 Unlike giant tube worms, the original digestive system of the laantaug never completely atrophies.↩

5 Methane is lighter than air, and the laantaug's burrow is warm enough to cause an updraft effect.↩

6 I'm calling out the inspiration directly so that you can look it up yourself if you need more detail.↩