Clam maybe?

[Darylb]

Found this thing this afternoon just wondering what it could be also found this other thing in my tank again has been there for a while never did get a positive id on it thanks in advance also the first picture of the brown thing is of it shriviled up the other one is of when it's moving

 

[MINItron]

First pic is a bivalve of some kind. Looks like it may actually be a scallop.

 

[tampa_nick]

Third pic looks like a nudibranch. Does it move?

 

[Darylb]

Moves around a bit doesn't bother my corals tho