What is this?

[menancyandsam]

Clam looking thing pointing up w/ the white middle. What ever this is it has being opening & closing by itself. Stays shut for weeks/months then opens up for weeks.

Could this be alive?

http://s87.photobucket.com/albums/k139/menancyandsam/?action=view&current=DSC02517-1.jpg

http://s87.photobucket.com/albums/k139/menancyandsam/?action=view&current=DSC02522.jpg

http://s87.photobucket.com/albums/k139/menancyandsam/?action=view&current=DSC02523.jpg

 

[Ohiomom]

looks like an empty shell of a clam...would say if it closes if you "tap" it then it is alive..otherwise opens and closes with current or fish movement..just my guess.

 

[Thunderstruck34]

looks like the empty shell of a spiny oyster...or a hitchhiker oyster of some sort.