This strange looking nudibranch is known in Japan as the Pikachu sea slug.
Amongst the Japanese it is very popular and believed to be the inspiration to create Pikachu, the beloved Pokémon.
In Thailand dive guides refer to it as ‘Bugs bunny’ because of the ear-like appendages: the extrabranchial and extrarhinophoral processes.
The proper name of this beauty however is Thecacera pacifica.
A member of a genus with many undescribed species!