ID please

[coralfever]

Any body know what this is? Bi-valve of some sort maybe. Came in on some live rock and has doubled in size over the last three months. Thanks in advance.

 

[LeslieH]

Either a clam or a solitary tunicate. Hard to tell with the photo. If the siphons can fully retract it's a clam. Either way it's a harmless and even beneficial filter feeder.

 

[d9sccr]

I would say that it's def. a tunicate..we just finished looking at them under a microscope and I saw two that were identical to that one.