Say hello to the nudibranch. ^_^
There are over 3,000 different species of nudibranch. They are marine gastropods who lose their shell once they reach the end of their larval stage. The color and shape varies by an extraordinary degree making each of the species visually stunning in their own way.
Some nudibranch have cerata, a venomous appendage that contains the remains of the nematocytes of the creatures they eat. They are also capable of eating plant life and using the chloroplasts within to fuel themselves. Quite a resourceful critter.
Many of the toxins used for protection by the nudibranch are not deadly, but instead incapacitate their predator in some way while the nudibranch makes its escape.
They are hermaphrodites, but do not fertilize themselves.These things are awesome. All the coolest (and most horrifying) things live in the sea.