Pikachu Nudibranch

Thecacera pacifica is found across the Indian Ocean and western Pacific. Some reported sightings also include The Gulf of Mexico, but these are unconfirmed. It is a rare species, and sightings are regarded as special. 

Like many similar creatures, such as sea slugs and other nudibranchs, experts prefer not to refer to them by their common name. The scientific name is far more reliable. However, in this case, the common name is very popular.

Pikachus are exciting to spot on a dive, even if you're not someone who's particularly interested in nudis. And if you do see one but you don't care, please highlight it to other divers in your group, or to your guide, because these little chaps are very popular and you will be thanked.