"KurtG" wrote in message .. .
Pszemol wrote:
Maybe snails just got eaten when already weak or dieing ?

Or, when the hermit is hungry. Often the snail wins although he's
usually left on his back.

Most of the snails we keep in our tanks have opercullum,
which is tight fitted "doors" to their shells. When bothered
by crabs/shrimps or other opportunistic predators like this
they retract to the safe home and close their doors behind.

Crabs cannot eat healthy snails - only sick/weak/dead ones.

A different story is with predatory snails attacking other snails.
They inject venom and paralyse & kill the snail before it
can retract to their safe heaven shell.