This small nudibranch is a rare find — especially moving at a good clip across the sand in broad daylight.  It is more commonly found at night wandering about Halimeda beds or exposed rocky sites. This little one was between 15 and 18 mm or 3/4″ at best.  Found in less than 8 ft  or 3 metres of water in Ma’alaea Bay, Maui.  For more information and photos please see Sea Slugs of Hawaii.