Bit random, I know, but I just couldn't resist posting about this most bizarre creature.
Courtesy of the doubtful guest, here's a photo of the pelagic sea slug (also known as a blue dragon which sounds so much better) which generally floats around the sea on its back. In this pic it is not floating but on the beach. I also know that this is the tummy not the back. I am clever me.
Scientific factoid stuff here as well as a couple more pics.