This is one of those fairly common, rarely seen nudibranchs. It can vary significantly in colour, but maintains its warty appearance, notable yellow rhinophores and bright yellow foot. The 5 cm or 2″  individual photographed here was found in approximately 2 metres (6ft) of water in North Kihe, Maui.  They are primarily nocturnal, so this was an unusual encounter.  For more photos and information, please see Sea Slugs of Hawaii.