Nudibranch? Good guy or bad guy?

[kvinnyy]

Hi, came across this little guy during a dip. I'm guessing it's some kind of nudibranch. Does anyone know? Is it okay to add into my tank?

 

[JoJosReef]

I've removed every nudibranch that came in with my live rock. Too much of a risk it'll eat my corals. I donated them to a local reefer trying to raise them, and turns out they do eat aiptasia!

 

[damsels are not mean]

Looks like an elysia to me which would be reef safe but will almost certainly perish without a lot of a specific kind of macroalgae (depends on the species) I am really not sure on the ID and outside of those and a few ugly algae eaters I believe almost every nudi in the sea is either not reef safe or completely unsuitable for hobbyist aquariums due to a specific diet. I would not ever keep one if I was not 100% sure what it was and that I could keep it.

 

[taricha]

green guy. lean toward algae eater - elysia or related. I'd keep it.