Aplysia

:  any of a genus (family Aplysiidae) of large, sluglike marine gastropod mollusks that lack a shell or have a reduced internal shell embedded in the mantle and that have a pair of lateral winglike extensions on the foot and a pair of sensory tentacles at the front and top of the head ◆Mollusks of the genus Aplysia feed chiefly on algae and usually discharge a purple ink when threatened. The common name “sea hare” is often used for species of Aplysia and related genera. The animal he settled on was a lumpy mollusk called Aplysia californica, a large sea snail that you will never see in a wildlife calendar. It looks like a purplish-green baked potato with ears. — Stephen S. Hall, New York Times, 15 Feb. 1998