This appears to be a newly documented, unidentified flatworm, hence the ambiguous title — the Eryleptid or Pericelis part being a suggestion of Cory Pittman’s.  This beautiful little animal was found crawling through the middle of some grey sponge on a rocky, sponge-covered reef in less than 2 metres of water.  Ma’alaea Bay, Maui.  I believe it to be nocturnal, but when it was found moving about in broad daylight, its colour was a lovely coral, graced with deep rose-coloured spots and a white speckled margin that continued onto its pseudo-tentacles. As it moved into the shadows and attempted to bury itself in the sponge, it shifted to a darker rose colour  with the spots remaining quite distinct..   Approximately 12-15 mm. (1/2″)