I've had 5 snails die in a month & a half. I've lost 2 turbo snails,2 nasarius snails & 1 Trochus Snail.The trochus snail died a day or so after I got it, the last turbo died last night.My wife said this morning the Emerald crab was picking at the shell,I'm assuming the crab did not kill it but was just picking at the empty shell? The water parameters are fine.I'm doing 10% water changes once a week.The only things in the tank are a pair of clowns,a fire shrimp,Emerald crab(small) & a little red star fish.Sorry I don't know the species I got it at Rose City and forgot to ask Nick the name of it.The tank is a 29 gal bio cube.Sorry if I'm rambling I'm just throwing as much info as I can out there.