Eubranchus farrani (Alder & Hancock, 1844)

7 April, 2013.
Elizabeth Rock, Ardnamurchan on the west coast. 
15 mm animal at 12 m. Water temperature 5.9°C.
Sony NEX-5 in Nauticam housing, 18-55mm lens, SubSee +10 dioptre and 2 x Inon D-2000 flashes.