Identify, please?

[mgregg99]

My wife purchased a rock with an oyster, some mushrooms and an unknown item on it. The item we need help with is some kind of filter feeder that is living in a shell casing that it sticking out from the oyster shell. The casing is about an inch long and about 1/2" wide and at the open end you can see some kind of mouth. About every 10 to 15 minutes or so this mouth opens up and a fan type of extension comes out and sweeps towards the mouth. We didn't notice this in the store or we would have asked. We're stumped as to what it is.

Anyone have an idea?

http://www.itsmygallery.com/samples/mysteryfan01.jpg

http://www.itsmygallery.com/samples/mysteryfan02.jpg

Thanks!

Mike

[Paintbug]

that would be a barnacle. just a friendly filter feeder :D