dead turbo snail bad? crabs are eating it..

[Delphinus]

I find I can always notice when a snail has kicked off. The tank has a bit of an "off" look to it for a few days. If you pull that snail out now before the flesh is all gone, for example ... it will be in your top 5, maybe even top 3 most-foul-smelling things you've ever smelled. It's probably not that great to leave in there. However that said, my tank is littered with snail shells of those that didn't make it, and the tank lives on. I pull them out every few months or I let the urchins pull the shells out of crevasses and then I pick them off the urchins.