leopard sea cucumber
Has a ring of paddle-shaped, black tentacles around mouth that pull off the layer of organic matter that settles on the sand.
Has cuverian tubules (toxic white sticky threads that are attached to the respiratory tree inside of it) that are used as a defence.
This species is famous for having not just one but often several (40 being the record) fish that live up its bum.
Not only that, while up there they communicate to each other using sound so that when you see one of these sea cucumbers listen , and you may hear the party inside.