The more we study the oceans, the clearer it becomes that the land got screwed in terms of the quality of our soft invertebrates. This diaphanous, scrimshawed angel is the ocean's version of the slug. It's vicious, but it's beautiful.
Sea angels are aqua-slugs that have lived in the ocean long enough that the "foot" that runs along the bottom of most gastropods has split and become the wings they use to flutter around the ocean. They're tough to find, both because they're only five centimetres long and because they live in colder parts of the oceans.
There are a few different species of sea angel, but the one you see above is Clione limacina. This one is a relentless hunter of tiny sea snails, and has a special proboscis for prying them out of their shells so it can eat them.
But, you know, it's pretty.
Top Image: Kevin Raskoff, Hidden Ocean 2005 Expedition: NOAA Office of Ocean Exploration. Second Image: Wiki Commons.