Snails are on the list of "gross but innocuous" creatures that most people look at without a second thought. The French eat them, but most people overlook the array of amazing slugs, let alone amazing snails.
Snails made most of those awesome shells you can pick up at the ocean. Conches are snails; like oysters, they produce valuable pearls. Conches will probably get their own entry at some point, but for now...
The slug in there is quite pretty, too.
There are some snails that can actually kill you. No, they do not feed on human flesh like something out of a horror flick; their poison just so happens to affect fish and you.
It's a shame, 'cause these are some REALLY pretty shells!
The snails in the genus Conus, AKA cone snails, are all at least mildly venomous. They are easily recognized by their simple, fairly smooth shell with a giant point towards the tip. They eat fish, marine worms and even each other with one of the most awesome weapons possible: A poisonous harpoon in their shells.
The harpoon I knew about. The swallowing I did not. Holy carp!
Cone snail stings range from 'mildly irritating' to 'put you in the E.R.' The smaller species are generally safe; the larger ones can puncture wetsuits with their little harpoons and hit you with a nasty dose of tetrodotoxin.
Yeah, that poison again. You saw it in pufferfish and the blue-ringed octopus. It causes severe paralysis; if it reaches the lungs, a single shot is deadly. As always, some of the most lethal snails are in Australia.
There is no antivenin for this snail's venom, but pharmacists, being pharmacists, are messing with it anyways. Despite being scarred for one's remaining life, paralysis is generally one of the least painful ways to go out; pharmacists are interested in turning this deadly poison into a painkiller.
Oh, those crazy pharmacists. Surely there is no way this could go wrong.