I.D. please. Nudibranch??

[junyoungmin]

I found 3 of these on a new rock from the LFS, they look like nudibranches. white with fluffy looking snowflakes coming off their backs. the rock had a colt coral on it but it fell off or tore off. are these things eating at it? are they bad to have?
I tried supergluing the colt back on the rock and one of them went straight toward the colt, i found it knocked off again. is there a better way to attach the coral or will it die anyway from tissue damage. thanks for your replys

thanks again for all your replys

 

[spanko]

Yup look like nudi's to me. Pluck them out probably. They are gonna die when whatever they eat is gone anyway.

 

[reefreak29]

Tritoniopsis frydis, they feed on gorgonians can range in color from white to orange.
or a Tritoniopsis elegans they feed on soft corals.

 

[coraljunkie]

Had the same thing in my tank. Found it munching on my toadstool leather. They are bad.