If you've spent time at the beach, you may have seen the abandoned shells of cone snails, many of which look like naturally-formed works of art (they're often polished and turned into jewelry). But if you ever see a live one, we strongly advise against picking it up... because that innocent-looking exterior houses a venomous, carnivorous predator.
The venom of the cone snail is a powerful neurotoxin, which can paralyze a fish many times its size, and there have been over a dozen confirmed reports of humans being killed by the larger species (which can grow to over six inches long). Most species are non-lethal to humans, but their sting can still do some serious damage.
But that's just part of the horror... at least if you're small enough to fit in this thing's mouth. When the snail zaps a fish with an organic harpoon full of the toxin, it undergoes a horrifying transformation, morphing its body into a giant vacuum of death... as you can see in the video below from National Geographic: