Pyramid Snails

Within the last two days I have had three of my large snails die. Curiously, as the crabs were devouring the upside down snails, I noticed a bunch of tiny white snails along the bottom of the shell. They were positioned just on the exterior edge of the shell where the occupying snail can be seen.
In these two pictures, you can see where the tiny snails are located. Every single astrea snail I have, has these small snails on them. Oddly, my Margarita snails and ceriths do not have these on them. When I first saw them, I thought that maybe they were baby astrea or cerith snails. With the sudden deaths, I soon realized they were not.

I will have to do research on these. From what I have found so far, these are typically clam predators. There have been a few reports of some types of pyramid snails that go after astrea snails. From what I have read, the best course of action is to knock off the adults and use a brush to remove any eggs. Without a host, they cannot survive. With a clam, you would need to remove the clam to another tank and wait for the snails to die off. I will not be able to remove all of the snails, so I will have to pick them out, and brush them off. One by one.