The Sea Snail is a rare enemy that spawns in the Ocean on either end of the world, usually during the night. Even then the spawn rate is still the lowest of all enemies in the Ocean, one third that of Squids. It slowly crawls along the sea floor.
It closely resembles the Syrinx aruanus (commonly known as Australian trumpet or false trumpet), the largest extant snail (shelled gastropod) species in the world, and the largest (heaviest) gastropod in the world.
The Murex sea snail was used to create purple dye, it was so rare that its value was its own weight in gold. This is also why most countries do not have purple in their flags.
The Bestiary entry for the Sea Snail: "This unusually large snail makes its home deep in the ocean. Its mucus can be manufactured into a purple dye."