No - these snails were definitely dead. One of them the body had actually fallen out of the shell and was completely solid.
These things are just simply too big to be threatened by anything else in the tank (it's a peaceful, non-predatory tank - the only slightly predatory critter I've got is a large green brittle star and he shares his caves quite happily with very small peppermint shrimp!).
Water parameters? They are pretty constant - PH
:8.5, Nitrite:0, Ammonia:0, Nitrite: <5. Salinity: 1.023, Temp: 81-82.
I am, however, battling a cyano
outbreak at the moment - it seems to be coming under control slowly - but did I read somewhere that this stuff can be toxic to these critters???