The African Plate and the Indo-Australian Plate meet together deep beneath the surface of the Indian Ocean in a long line of tectonic divergence known as the Central Indian Ridge (CIR). As new seafloor is created hydrothermal vents pour out molten hot fluids rich with minerals and an alien landscape is formed. The hot minerals precipitate to form high cylindrical chimneys called smokers and strange communities of life form along these structures. This ecosystem is entirely based upon chemosynthetic archaea (ancient one-celled life forms which take energy directly from the oxidation of inorganic compounds). Great communities of eyeless shrimp, giant tubeworms, and annelids support themselves on the archaea. Among the strange creatures is a very weird gastropod mollusk, the scaly-foot snail (Crysomallon squamiferum), which is different from every other mollusk (and indeed every other animal) because of the material it uses for its bizarre scale-mail armor.
The scaly foot gastropod has an armored foot which is covered in little scales made of iron sulfides. Additionally the deep-sea snail has a triple layer shell. The outermost shell layer is composed of iron sulfides, the middle is a thick protein coat, and the inner shell layer is composed of aragonite (a calcium carbonate).
I wish I could tell you more about the habits of this snail but since it is found in super heated water at the bottom of the Indian Ocean, it has not been extensively studied. However, The US military is interested in the creature as a possible inspiration for next generation composite military armor so maybe we will all learn more about the scaly foot snail.