How can I tell if a clam has died?

[dooleyb]

I think my clam is dead but how can I tell for sure. The shell is open a bout an inch or so. The clams is withdrawn about halfway back into the shell. It is not responsive to light or anything. It still its color but is gapping severely. I noticed a couple of snails down inside the shell on the clams mantle. I don't want to remove it until I am sure it has succumbed.

Thanks for your feedback.

[mbbuna]

if snails are eating it its dead