What is this thing???

[thepomonacow]

I am having a hard time figuring out what this is. I noticed it on my live rock when I bought it. It looks a little like a clam but with nothing inside it. It is about 3/4" long and 1/2" wide.
I have a picture of it(my camera is not that great though):
<a href="http://www.turkeyburritos.com/whatsthis.html" target="_blank">http://www.turkeyburritos.com/whatsthis.html</a>
Thanks,
Jay Pedersen

 

[naturelover]

I visit LFS atleast twice a week just to look around.

 

[naturelover]

sorry about that post..suppose to goto other thread but got here some how. I took a look at u r pic..it's hard to see anything. But if it's an ovel shape with slight white spot between rock and the thing then it might be a limpett. They r great cleaners.