Some sort of bivalve or something on my rock

[Treezer8]

There are about 4 or 5 of these on part of a rock in my tank.
They look almost like a clam or oyster or something, and have green/yellow branches coming out of them. They also have what looks like a mouth that extends out, and looks like a funnel.

Here's a pic

 

[Treezer8]

any ideas? :(

 

[little_fish]

A turkey clam or some other sort of bivalve?

 

[Treezer8]

Looked up turkey clam but no luck =\

They almost look like they're built INTO the rock, and you just see them open and close with their big funnel mouths poking out, and the bright green/yellow branch things. I'm turning that rock into a zoa rock and I just need to know what these are before hand

 

[little_fish]

I think they are some sort of bivalve, not anything to be worried about

 

[Treezer8]

I hope not. There's about 5 of them and I hope they don't take over the rock lol

 

[Treezer8]

Bump.
A few more have popped up now, and it looks like the zoa's near them close up quite a bit

 

[jase]

They are harmless filter feeders but if they are annoying ur zoa's u might want to try to remove them