I saw this cool pic off of the Carnivora forum of a snail called the Scaly Foot Gastropod a.k.a Iron Snail (Crysomallon squamiferum). It's found in abyss near black smokers. The cool thing about this snail is that it's shell and it's scales on its foot are composed of iron sulfides where as most snail shells are made up of calcites. The iron sulfides make the shell real tough especially for crabs that try to crack it. It's shell is being studied by the U.S. military for armor development. Used HB, 2B, 4B pencils for the shading.