Hi Kris, Highly unlikely that they are parasites of the snails. You said they are "maggot-like", and almost certainly that's just what they are, common fly maggots. It doesn't take flies long to find somethind dead and lay their eggs on it. Some years ago a couple of friends and I did some collecting in a dumpster in back of a scallop shucking plant in Maine. We got some nice shells, but it wasn't the most pleasant collecting I have ever done. In addition to the smell, there were GALLONS of maggots. Paul M. Rhode Island