This, apparently, is a flatworm that is rarely seen in Hawaii and its presence was even doubted until a recent sighting.  It could be that this worm hides out in places that tend to be out of most diver’s comfort (i.e., the shallow shallows) as I have come across a number of these worms and 2023 has proven to be a rich one. All sightings have been in less than 2 metres (6 1/2 feet of water) and all in rocky/rubble and dead coral habitats in South Maui or Ma’alaea Bay area.  John Hoover goes into great detail re the first Hawaiian sightings of these beautiful worms and it’s definitely worth checking out his sight and the story around its particular name.