This beautiful flatworm remained completely oblivious to my presence for several minutes.  It was approximately 15 – 18 mm and was found in less than 2 metres of water in a rubbly area of rock and algae in the Makena area of Maui. It was new to me, but Cory Pittman has documented it in a lab and another underwater photographer captured one off the coast of the Big Island, Hawaii.  More details can be found on John Hoover’s Flatworms of Hawaii site where you will also see how varied this animal can be in colour.  One of its defining features seems to be an obvious mark on the back end of the worm that replicates the colouring of the pseudotentacles to some degree.