Is this good bad or indifferent (nudibranch id)?

[Bigben7]

Ok, I found this guy crawling on my glass today:

And here is his handsome profile:

For reference, he is 1 cm (slightly less than 0.5" when fully stretched. Basically, to my knowledge there are no beneficial nudibranchs except maybe sea hares. I have had live rock in my BC 29 for 6 weeks, and have only in the last two weeks added 9 snails, 2 scarlet hermits, 2 cleaner shrimp, and a 10 polyp frag of palythoas.

Did this come in on my live rock? Should I terminate him/her live? What is it?

Thanks

 

[shane clayton]

not a nudibranch

not a nudibranch

doesn't look like a nudibranch there's - no "nude branch" or naked gill structure. but the two "ears" indicate a member of the genus aplysia - sea hares. probably. it's either a small species or a juvenile hitchhiker.

 

[pagojoe]

Yeah, it looks to be a sacoglossan slug (although arminid nudibranchs don't have external gills, either). It's probably an Elysia species? One of the real sea slug experts should show up soon and straighten us out.

Cheers,




Don

 

[pagojoe]

...and to answer your question, that would be "good."

 

[greenbean36191]

Yep, it's Elysia so you can count on it to feed on macroalgae of some sort. Possibly Caulerpa.

 

[Bigben7]

Thanks for the replies. He is back and home free in the aquarium. To tell the truth, he is actually kind of cute...