I recently experienced a snail dieoff.About a third of my 15 or so turbos croaked.Funny thing is that they were the smaller ones.Also I had tried to introduce some bumble bee snails,and the blueleg hermits made use of them within the hour.I even have lots of empty shells in the tank for them to swap out.Guess the bumble bee shells came with a free meal!As for my turbos...I suspect my hawkfish.He's been a real pain.Killed my peppermint shrimp,emerald crabs,hitch hiker crabs,and keeps my watchman goby constantly hiding.Maybe there is some sort of mystery tubo snail virus going around.