Flail snail

Body plan
Flail snails have many of the same anatomical structures as their more diminutive land snail relatives. Their head contains a primitive brain and is connected to a mantle that extends out of the snail’s shell. Flail snails propel themselves with the use of a muscular foot and the secretion of a unique iridescent mucus, commonly called shimmersoap. Adult flail snails can reach the size of a fully loaded wagon and weigh more than 900 pounds. A fully grown flail snail’s shell comprises only a fraction of their total weight, clocking in at only about 250 pounds.   Tentacles
Unlike other land snails which navigate using a single pair of tentacle eye stalks, flail snails grow between four to six tentacles. These tentacles are not only used for navigation, but also for defense. Complex muscle systems in the tips of the tentacles can rapidly change the tentacle’s texture and harden into ridged spikes. These clublike tentacles can then be swung at predators with frightening strength, thus earning the flail snail its memorable name.   Mucus
As previously stated, flail snails—like other land molluscs—secrete a mucus to help keep their soft tissue hydrated. This also lubricates their muscular foot as it moves across the ground, propelling the animal forward. However, in flail snails, this shimmersoap mucus is excreted along with the animal’s waste, leaving a trail of near-transparent liquid. This substance quickly hardens into a glassy residue called shimmerglass. Though shimmerglass is inedible to almost all subterranean lifeforms, its composition makes it an extraordinarily effective material for arcane enchantment.   Shell
Like other snails, flail snails grow a protective shell on their back. Yet, while most mundane molluscs grow shells or beaks from ingesting calcium carbonate, the flail snail shells are made of a refined form of natural crystalline shimmerglass. These shells have a number of unique properties. Their robust crystalline structure actually refracts arcane energy, trapping the magic within the spell for a short time before releasing it back in the direct it was cast. Additionally, because a position of the magic expelled at the snail is retained by the shell, many common magical effects or items simply have no effect on a flail snail.   Flail snail shells can even generate their own magic if need be. When disturbed, a flail snail can cause their shell to emit dazzling, coloured light for a few seconds to temporarily blind anyone within a sixty-foot radius. This ability can temporarily stun most foes that venture into the snail’s habitat from above ground, though it is largely ineffective against its more common subterranean predators.

As a snail grows, its shell grows to fit the animal's body comfortably. The new material is added to the edge of the shell aperture (the opening of the shell). Therefore, the center of the shell's spiral was made when the snail was younger, and the outer part when the snail was older. The shell forms a logarithmic spiral, with the majority being held to the left, or sinister, side of the snail’s body. When the snail reaches full adult size, it may build a thickened lip around the shell aperture. At this point the snail stops growing, and begins reproducing.

Flail snails highly adapted to subterranean environments. They prefer to live in caves with access to water or that have a high degree of humidity, as this helps lubricate their foot for locomotion. They are easily injured by UV radiation and avoid sunlight whenever possible. Because of their diet and their need to secrete shimmerglass as a waste product, flail snails require a large amount of space to roam without retracing a recent path. This forces flail snails to be almost constantly on the move, as they search for untouched sections of cavern floor to excavate.

Flail snails are elemental creatures and thus do not require the same biological caloric intact that most carbon-based lifeforms do. They subsist almost entirely on silicon-based food sources such as rocks, sand, soil. In particular, flail snails voraciously consume crystal growths and soil deposits rich in minerals. This, along with the guano, fungi, and lichen that inevitably is consumed along with their intended diet, helps produce the shimmersoap and shimmerglass that they make their shells from and leave in their wake.   Some have claimed that flail snails also consume precious metals and ores, much like the much-maligned rust monsters. However, despite both being organic creatures that subsist on silica-based food sources, flail snails cannot digest worked metal or even raw ore in the same way that rust monsters do. As a result, most flail snail colonies avoid mining operations not because of the presence of mortals but because of the toxicity of the regions' mineral content.

Some communities have managed to import flail snails and begun to breed and herd them in underground tunnels. The hope is to create a sustainable source of shimmerglass that can be scaled to meet the demands of the market. However, flail snail herding is a dangerous and difficult business. It requires vast amounts of space for the snails to roam, as well as a large amount of laborers to guard the snails and then process their shimmerglass waste. Conditions in these tunnels are often abhorrent, with workers on duty for twelve hours or more in tight, smelly, and dark environments. Cave-ins and attacks from smugglers or the snail's predators are common, and the animals themselves can easily become agitated in a commercial setting.

Shell Harvesting
The flail snail is one of the most coveted subterranean creatures in all of Holos. A single flail snail shell can weigh as much as 250 pounds and be used in dozens of arcane industries. A single intact shell can sell for upwards of 5,000 gold royals.   Most hunters seeking flail snail shells desire them for their antimagic properties. A skilled armorer can make three shields from a single shell, though in the process, the material's antimagic begins to decay. After crafting, a flail snail shell shield gives the wielder the snail's antimagic trait for about a month. After this point, the shield's antimagic begins to decay, essentially becoming a spellguard.   Flail snail shells can also be ground into a powder and used to create the dye for a robe of scintillating colors. While most items like a robe of scintillating colors require additional rare and magical components to complete, dye made from flail snail's shell already contains the necessary magic required to craft such an object.   Shimmerglass Production
While both antimagic shields and robes of scintillating colors are highly expensive and sought after magical items, flail snails have also been captured and tamed to produce another rare good: shimmerglass. While not immediately as expensive as an intact flail snail shell, shimmerglass is extremely useful in alchemy and the enchantment industry.   Even unrefined, shimmerglass has traces of magic within its organic structure. This gives it both physical and arcane durability. Its glass-like structure allows it to be cut, heated, and spun into a variety of shapes and thicknesses, giving it a flexibility that other materials such as greenstone or shadowglass do not. Finally, the trace magic within shimmerglass allows an enchanter to imbue objects made from shimmerglass with more powerful spells without the risk of metaphysical tearing or alchemical side effects.   All of this means that arcane goods made with shimmerglass are often made cheaper and faster than items imbued through other means or ritual alone. All of this makes the demand for shimmerglass extremely high, but due to the nature of shimmerglass harvesting, supply of the substance remains unable to meet the market's expectations.

Flail snails are naturally subterranean creatures, preferring to live in damp, underground cave networks. As a result, much of their perception abilities focus on detecting movement in the pitch black. Flail snails can detect movement within sixty feet thanks to this tremorsense. However, even without this ability, flail snails retain their sight. Their complex eye stalks still contain light sensitive eyes which can make out grey shapes within 60 ft. even in total darkness.