2.78 kilometers (1.7 miles) underneath the surface of the Indian Ocean, hydrothermal vents are spewing out water around 350°C (660°F). Even in these extreme conditions, diversity is abundant for those lifeforms which have adapted to the seemingly inhospitable ecosystem. One of the wackiest and most impressive creatures from this particular area is the scaly-foot gastropod (Crysomallon squamiferum), a snail with a shell of iron and plates of chainmail covering its otherwise squishy foot. This is the only animal in the world with a skeleton made of iron: two types, pyrite and greigite,* encrust scales of conchiolin – a hard, horn-like substance that coats the shell and parts of the foot.
The complete functionality of armor and scales is not entirely clear – it’s possible they exist for protection against predators. Another hypothesis suggests that bacteria living on the exterior of the snail assist in detoxifying the noxious sulfides ejected from the ‘black smoker’ vents, resulting in the growth of the iron sulfide armor. In addition to this just being awesome on its own, researchers at MIT are curious to know if the snail’s design could help inspire other types of armor.
Additionally, the snails are just massive, considering their environment. Food sources are scarce down there, but these guys don’t even need to eat – they get all of their energy through a process of chemosynthesis, in which the bacteria living in their guts produce the nutrients required for sustained life. As a result, these snails are about three times the size of other hydrothermal vent snails.