Ceratosoma amoenum, or the clown nudibranch, is a species of colorful dorid nudibranch, a sea slug, a shell-less marine gastropod mollusk in the family Chromodorididae.

[2] Ceratosoma amoenum is a common nudibranch found in the intertidal zones of temperate southern Australia and northern New Zealand.

[3] This species has a white body which is elaborately patterned with orange and purple spots especially on the dorsum.

The size of the spots varies according to range, with those individuals in New Zealand having the largest.

It has been seen feeding on sponges from the genus Semitaspongia and the species Dysidea fragilis.