ID nudibranch!

[cyenna]

 

[Travis L. Stevens]

What was it last seen crawling on? It's most likely an Aeolid nudibranch, which is a prey-specific predator.

 

[cyenna]

last seen on my zoanthids

 

[LeslieH]

Most definitely the as yet unidentified zoanthid-eating nudibranch. If you prefer your zoanthids to having tiny nudis you'll need to carefully check over the colonies for nudis & their eggs then remove them. There are tons of posts here on RC concerning the best way to get rid of them.