It seems to me they shouldn't be attacking the clam. Maybe the clam is distressed and they are capitalizing on its weakness.
How about if you put some food of some kind nearby the clam, a diversion, so that the 'pods will maybe go after that instead, while the clam tries to recover?
I don't really know what to suggest. I'm somewhat new to clams myself. So maybe someone else who REALLY knows what's going on can jump in here and suggest something.