Clams? Hitchhiking

[GiantBen]

I found some clams (I am calling them that, correct me if I am wrong) in some LR I bought. Two long skinny ones that were in some burrows in the rock and one larger one that was in a crag in the rock. I pulled them all out of their hiding places, because I didn't want to have to pull the LR and get at them later. One of the little ones didn't make it, but I left the other two in the tank. They are alive. The larger one has relocated to hang under a rock as well. The big one used to have what I guess is a dead appendage sticking out if it, but it dropped it last night when it moved (pic of when it had it in my tank thread).

 

Does anyone know what these are?

Can they harm my system?

Can they help it?

Will they survive the cycle?

 

I'm not sure they are worth keeping in the tank, but for now they are the only thing in it. I am most worried that they will borrow and die, and I'll need to get them out.

 

SMALL ONE

 

BIG ONE

[Urchinhead]

Looks like some form of muscle. Mostly harmless and possibly helpful in terms of filtration of stuff unless it kicks off then either have a good CUC or get it out before it messes up your tank.

[javisaman]

they are bivalves...good hitchhikers. I've got dozens of them.

[GiantBen]

Okay thanks. Should I have left hem in their holes?

[javisaman]

Yea you should have, but no worries, they'll find another spot.

[GiantBen]

Would having them die in one of the holes be a problem? The small one's tip is frayed open now (like the pods opening in Alien the movie). Is it dead/dying? The large one has found a nice spot, so thats good.

[javisaman]

You'll have very minor spikes...nothing to worry about. Your more likely to kill them by trying to pry them out.