Hey I have something really weird in my tank!!


How big is piece thats moving,if it is really small it could a type clam thats opening and closeing.I had one about 1'' long that I thought was a rock until I moved it around to see the opening.


New member
I have them in my tank they are a type of barnacle. They wont move around but when they pop up they open up and filter feed. They are good to watch.


In Memoriam
Crab. But below the snail it looks to be a clam covered in coraline incrusted in the rock. But you say the whole rock moves. Crab.


New member
The piece moves up and down the long skinny piece will go up then down. If you put something on it it will also go up


Premium Member
It might help if you circle or point to exactly what you're talking about, because there's a lot of stuff in the picture and you're going to get a lot of different answers. If you're saying the entire top part of the "rock" moves then it sounds like a clam.


I am not a boy!
I say clam as well. If you put that rock there to act like a bridge over the other two, you may have set it right on top of the clam on one of the other two rocks.

These clams are filter feeders and are much hardier than the fancy ones that most reefers buy to put in their tanks (maxima, crocea, etc). I have had them survive full tank cycles. Pretty neat hitch hikers