C. trilobatum is characterized by its unbroken mantle edge around its head and up to its gills. Its dorsum's color can vary from pale green to orange-red or brown, and usually mottled and spotted with lighter colors.
This dorid nudibranch looks deceptively similar to two other species in the same genus: C. gracillimum and C. trilobatum. What distinguishes it are the three mantle lobes on each side of its body -- on the side of its head, the side of its gills and another in between.
C. gracillimum is similar in appearance to Ceratosoma tenue (and, to a certain extent, C. trilobatum), but can be distinguished by the absence of a mantle edge between its head and the lateral lobes. This nudibranch can grow up to a maximum length of 12cm.
tiny shrimp (?) above the Ceratosoma nudibranch