This relatively large (40 -50 mm?) Pseudobiceros 5 was discovered by a fellow snorkeller, Allan B. It was just cruising across the sand in a few feet of water — a rather rare occurrence.  The photos of it taken on a rock are a result of moving it to a safer place — out of the way of many humans walking across the sand.  Depending on the light, its colour shifted from a dark brown to a deep purple to a lighter brown with consistent white spots and yellow spots and markings toward the margin and pseudotentacles (see close-ups in photos).  On John Hoovers, Flatworms of Hawaii site, he provides a common name that I think is most appropriate. His words: Privately, I refer to this worm as Pseudobiceros kikokiko (which means “spotted” in Hawaiian). I hope whoever formally describes it will consider this for a scientific name. It’s a kikokiko to me and always will be!