Clams on LR?

[BurN]

I bought some LR off of FloridaLiveRock and a few pieces had clams cemented to it. I figured they were just shells but recently I have seen a few of them open and close slightly. Could this be life? I went to the site where I got the rock but no clams were on the species list. Whats up?

 

[Cearbhaill]

Bivalves of some sort. My FloridaLiveRock was covered in them.
I tend to remove the huge ones (big screwdriver) so they don't open and shift my rocks around. I keep the smaller ones or any that aren't in my way- they are fun filter feeders.

 

[mogurnda]

There are a few kinds I have seen. Turkey wing arks are large, traingular, have a single opening all the way around (instead of siphons) and are attached by a byssus holdfast. There are also several kinds of oysters, in which one shell is permanently glued to the rock, and have a pair of siphons. They seem to do OK living on whatever floats in the tank, although I have not had one make it past about 18 months. Regular addition of DTs, Reed Mariculture's post-set mix, or some other phytoplankton mix would probably help them alot.