White blotches???

[Tautog]

I've noticed these white blotches on my live rock and dead shells. I later collected a slug-like, nudi, or something else. Could it be a stomaslios snail? It has no shell. It took the paint off my live rock, and cleaned my large clam shell better than bleach.

 

[DannyB]

Do you have a picture of the snail?