This is a relatively common nudibranch, but it is often overlooked due to its small size (up to 17mm) and the fact that it does an excellent job of blending into its background. Look for them hiding in the midst of their prey — the eggs of other sea slugs. They take on the colour of the eggs they feed on and can vary in colour from a white/brown to orange/pink/red. As illustrated in some of these images, some take on a blueish colour, but I’m unsure as to what their food source would be. For more information check out Sea Slugs of Hawaii.