Mantis shrimp. Getting the mantis out would create a harder problem though.... Try lowering your Ca lvl (unless that is you have corals). I've also heard that higher temperatures induce spawning so you might want to try lowering the temp. Certain stars may also provide an alternative, probably in the area of the serpent star group. Most fish seem to love snails eggs from what I've heard, not sure about the species that would be best to devour them though. Eggs are highly nutritious from what I've read from posts. Also posting your parameters might help with figuring out a way to control their reproduction.