This close-up photograph of a Phylodesmium longicirrum highlights one of the strangest abilities of some nudibranch and sea slug species. Photosynthetic micro-organisms, called zooxanthellae, live inside the larger animal. Like plants, the zooxanthellae gather energy from the sun. The sea slug then harvests this energy from the zooxanthellae to feed itself. Amazing! Divers should be on the look out for Phylodesmium longicirrum in Indonesia, where it can grow to be as long as 12 centimeters.