This is a fairly common species, but I was only blessed with a sighting in the fall of 2022.  Perhaps I have mistaken it in the past for the Discodoris lilacina as they are quite similar at first glance.  This particular individual was quite small (10 mm) and was found in a rocky, surge zone near Makena Landing, Maui in less than 1 metre of water (inside of an old concrete block).  Unlike the lilacina, it has a noticeable margin and a softer more raised appearance. It’s generally less fragile and unlikely to autotomotize (drop parts of itself!).  Please see Sea Slugs of Hawaii for more photos and information.