Clione limacina, known as the naked sea butterfly, sea angel, and common clione, is a sea angel (pelagic sea slug) found from the surface to greater than 500 m (1,600 ft) depth. It lives in the Arctic Ocean and cold regions of the North Atlantic Ocean. It was first described by Friderich Martens in 1676 and became the first gymnosomatous (without a shell) "pteropod" to be described. Naked sea butterflies are very special in their predation process. Their mouthparts have three pairs of tentacle-l