Hi! Welcome to the discussion, and thanks for the clarification - it did look like you'd prepared them the day you caught them. When Mom fixed Helix snails she fed them on oatmeal or something (I don't recall precisely) for a few weeks first to purge them. Then, yes, cooked carefully for precisely the reason you name.

It does seem a pity Gresham's Law appears to apply to so MANY things one would like to keep...