When a friend first spotted this nudibranch cruising across the open sand in South Maui, we were all a little baffled.  It was clearly a dorid of some sort, but it was a good size (at least 6 inches or 15 cm) and the large, flowery tubercles were something we had never encountered. Fortunately, one of us had taken a look at the underside of this particular animal and she confirmed it was a plain beige/brown and there were no white spots visible (typical of the very similar Dendrodoris tuberculosa).  We had spotted a carbunculosis –a fairly rare nudibranch on Maui — and actually a smallish one. They get up to 15 inches or 41 cm!!!  For more information and some excellent close-up images of the tubercles and club-like rhinophores check out Sea Slugs of Hawaii and the Sea Slug Forum. It is not a great idea to handle the carbunculosa — apparently their secretions can be very irritating to the skin.