Mystaconcha wilsonae (E. A. Smith, 1886)
Uncommon in the Solitary Islands Marine Park. Specimens recorded from the Solitary Islands and Eden in southern NSW.
Found under coral slabs and boulders. Believed to feed on colonial ascidians.
Not usually seen by divers due to their habit of secreting themselves under rocks and coral slabs. Bright colouration may be a defensive mechanism similar to that of some nudibranchs. 'Velutinids are caenogastropod snails, closely related to the Triviidae. In most velutinids the shell is open and flattened, much like a small abalone shell (Haliotidae), and at least partially enveloped by the fleshy mantle. This gives them a fleshy shell-less appearance which often causes them to be mistaken for sea slugs. In most cases when they are crawling a pair of head tentacles will emerge from beneath the body, instantly showing that these are not opisthobranch sea slugs. Another character is the anterior siphon above the head which opens into the mantle cavity.' Bill Rudman, Sea Slug Forum. See siphon and head tentacles in lower photograph.