When I moved my clams, I just tilted the rock so that the clam was sorta hanging by it's foot & let gravity work it's way on the clam. Within a day or so the clam just let go & fell the short 1" or so onto the sand bed.

You may have to re-tilt the rock a couple of times as the clams moves around trying to see if it can get comfortable.

I only ever tried moving 2 of my clams & it worked both times without injuring them.

Obviously make sure they don't have too far to fall!

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