It looks like a sheet of plastic or fabric that was tossed into the ocean, but this is an animal. A jellyfish, actually, called Deepstaria enigmatica. Link -via the Presurfer
are you sure this is a deepstaria-enigmatica? presurfer doesn't link to anything that suggests any real scientific identification of the creature. many on reddit (where it was originally on) are saying it could be an embryonic sac of some sort!
There was a lot of wild speculation on YouTube (where it was REALLY originally posted) as well ("weather balloon!"). So I went to Wikipedia, and the page there links to this video.
No word on how to properly cook them.