Slender Ceratosoma Nudibranch with hitchhiking Emperor Shrimp

Ceratosoma gracillimum can be distinguished externally by the complete absence of the mantle edge between the head and the well-developed lateral lobes on each side, just in front of the gills. Can grow up to about 12cm in length.
Source: http://www.seaslugforum.net/find/ceragrac

A hitchhiking Emperor Shrimp (Periclimenes imperator) can be seen. Fro more info on P. imperator see http://www.projectnoah.org/spottings/10587875