I recently received 3 nassarius snails. Woke up this morning and 1 is on its back while the other 2 are still active. I am pretty sure it is dead but I will do the smell test. In the event it is dead how can I remove the snail from the shell so I can return the empty shell back to the tank without fouling up the water? I plan on getting a few hermit crabs in the future and would like some spare shells available so they wont go after the other snails.