Identify hitch hikers please

[Ivy]

I have something like that in my tank they breed (split) like crazy I was told that it is aptaisia. It dosn't seem to bother anything in my tank

Hmm. The rock it's on came from an established reef tank. I'm
not sure the employee was supposed to sell me live rock from
there as it has what I'm fairly sure are mushrooms on it.

Assuming the shop didn't just get it in, it's not hurting the little
shrooms, so I'm going to leave it alone.

Will peppermint shrimp eat really honking big aiptasia? These
aren't little delicate guys for sure.
thanks for the advice,
Ivy