found something in my tank, help ID please.

[hooked]

Hello all,

I have no picture sorry . I found something in my tank that I have never seen before. It is about 1/4 long and is green in color. It looks like 2 halves of a shell put together. I am not sure how it moves as I see nothing moving on it, all I can figure is that whatever is in it comes out by opening the shell. I found it in 3 different places so I finally picked it up to look at it and found nothing that could help. I put it on a rock and was checking on it for over an hour. It didn't move at all. I got up today to find it has moved . Can anyone help me out on this? It has moved up and down on the rocks so thinking that it has fallen off a rock is out of the question.

Thanks for any help

[Alice]

Is it a clam/bivalve of some kind? Sounds like one of the little filter-feeding bivalves in my tank. They do have a "foot" they can put out to move around and when they are feeding a feather-type apparatus (sorry, I don't know the real name! :0 ) comes out to strain particles from the water.

Alice

[hooked]

Thanks for the info Alice.

I had to post since I was at 666