what the heck is this?

[cregbeary]

I have something strange in my live rock. if it's not a mantis shrimp i have no clue what it is, but it doesn't look like anything i have seen in the pictures of them. he hides in a hole and has a shield sorta thing to completely shut himself in. he opens it up a crack during the day and a little more at night, but i never ever see him move. even if i put food right in front of him. if there is a sudden move or a bump he shuts himself back up in a blink.

http://www.craigberry.net/tmp/aquarium/IMG_0440.JPG

http://www.craigberry.net/tmp/aquarium/IMG_0442.JPG

http://www.craigberry.net/tmp/aquarium/IMG_0443.JPG

http://www.craigberry.net/tmp/aquarium/IMG_0444.JPG

thanks a million guys, this site rules.

 

[greenbean36191]

It's an arc shell, a type of small bivalve.