Related to the oyster and the snail, these are baby cephalopods of 6 different types, several of uncertain parentage. When startled, the little Cranchia (lower left) pulls in its head like a timid turtle. Sometimes I have spent 5 minutes examining a dish of live plankton before noticing an inch-long lobster baby that was swimming right under my nose. Even then it was revealed only as a pair of dark eyes, apparently swimming around all by themselves. I had been looking right through the body without noticing it. This transparency may make things difficult for us, but it gives un an x-ray-like ability to watch such processes as the beating of a heart. On the other hand, it must be a great advantage to a baby lobster which is being hunted by a fish to wear a cloak of invisibility that prevents the fish from seeing its prospective meal. We tried painting these transparent babies on white paper, and they looked... (https://archive.org/stream/195204_201512/1952-07#page/n73/mode/1up)