hitch hiking clam??please id!!

Just got back from lfs with a decent head of zoas on a small peice of liverock,when i moved them to the tank a shell popped off in my hand,it looks like a split pistachio shell but a little bigger and now it is opening up a little and theres a long tenticle thingy coming out.Any ideas??Can someone identify this??It was on the underside of the liverock.Sorry my camera sucks but heres a couple pics of it.TIA

 

Get a shallow tupperware bowl. Put some tank water and the clam in that. After the water stops sloshing around in the water, take some top down shots from various angles.

 

just looks like a hramless little clam. I have had several over the last few months, nothing to worry about.

 

Feeding the baby right now. I'm gonna be awhile. The tentacle is about an 1 1/4 inch long. Seems to be rooting for food. It's a very plain looking clam.

 

Are they photosynthetic or do they feed?

 

most of the time they are burried in the sand. You might see it on a rare occasion, but other than that they stay hidden, so I geuss they feed

 

if theres a tentacle thingy coming out, could it possible be a scallop of some sort? the shell looked more in the genre. but that could have been the blurriness

 

Most likely it's a filter feeder, if you could get a clearer picture we could ID it more easily.

 

i wish i could get a better pic,but as long as it not harmful,i'm cool with it