These side-gilled slugs are fairly difficult to see as they really look like a sponge or bryzoan, especially when lying flat or tucked into a hole or under a ledge. If you look closely, the pattern beneath the white spots is fairly similar to that found on the Polygon Pleurobranch, and given its colour it is often mistaken for that species, especially if the Pleurobranchus varians is actually missing white spots altogether.  This individual was  1.5″ or 37mm, and found on top of an algae-covered rock in a intertidal lagoon, La Perouse Bay, Maui. Cory Pittman and Pauline Fiene have some excellent photos of young, old, pairs, shells and eggs.