The cone snails or cone shells (family Conidae) are predatory marine snails found in coral reefs.
The shells of cone snails are often brightly colored, and have
interesting patterns, although in some species the color patterns may
be partially or completely hidden under an opaque layer of periostracum.
Some species of cone snails can grow up to 23 cm in length and are found in tropical or subtropical waters. There are about 500 different species. They are carnivorous, generally eating marine worms, small fish, molluscs, and even other cone snails. Because cone snails are slow-moving, they use a venomous harpoon (called a toxoglossan radula) to capture faster-moving prey such as fish.
Information from Wikepedia - http://en.wikipedia.org/wiki/Cone_shell