Wing snail (Clione Limacina) model 25 cm.
With its see-through appearence, and fins that looks like angel wings, this is an animal known as the naked sea butterfly, sea angel, and common clione. In reality this is a pelagic sea slug, meaning a snail without a house living in the open ocean. It is found from the surface to greater than 500 m depth, in the Arctic Ocean and cold regions of the North Pacific and North Atlantic Oceans.
Clione limacina is somewhat cannibalistic, and feed exclusively on other species of sea angels. In Svalbard, the life cycle of Clione limacina appears to be at least 2 years. It is a hermaphrodite, and breeds during the spring and summer. It is a prey of planktonic feeders, such as the baleen whales, which historically led to sailors naming it "whale-food".