It is very unlikely that your snails are baby Cerith. Check your clams and Astrea snails if you find the snails on them then they are Pyramidellids. If your Astreas and clams don't have Pyramidellids or you don't have any clams or Astrea snails, then your snails definately aren't Pyramidellids as they will die without a host. Then the snails you have are likely to be Rissoids. Rissoid snails are Pyramidellid look alikes, but Rissoids are good. Was that confusing?
