This teensy little nudibranch was not only hard to spot at a whopping 3-4 mm, it looks nothing like what you might be searching for in the opistobranch world.  It really just looks like a broken off piece of sponge or left over algae.  Until it moves or manages to draw attention to its bizarre, oversized rhinophores, it is likely to go completely undetected. I merely got lucky in that it was, very momentarily, crossing a background of red coralline algae and actually stood out. According to Cory Pittman, master of the Sea Slugs of Hawaii site,  this animal is moderately rare, perhaps due to its near invisibility!  Found in North Kihei, Maui in an area of broken reef, rubble and dead algae in less than 2 metres of water.