This little nudibranch was found in a shallow, old traditional fishpond in North Kihei on a small fist-sized rock in about 1.5 meters of water.  It appeared to be just another sponge or tunicate, but upon the slightest touch, its rhinophores popped up and its strange trumpet-like branchial gill became quite prominent.  In this case, the trumpet form is an illusion created by the tell-tale white band forward of the branchia  It has unusual and varied papillae — some tentacular (see image below), some more broken and low-profile. This is a white speckled, pinkish/brownish rubbery textured discodorididae.  It comes in a few colours and is oddly varied in flecking, papillae size and structure.  At first, I mistook it for a Lilac Dorid. See Sea Slugs of Hawaii for more detailed information.   To 30mm or just over an inch.  This one was about 20mm.