Does snail ever come out from their shell?
:m:

no, snails shell has protein matrix which has mineral crystals in it. It grows with the snail. BTW snail bodyparts have pretty good regeneration power(if you dont smash his nervous system), they can easly repair their shell and other body parts if stepped onto.

Some crab species do though. They adopt a shell. When they outgrow it they find a larger one.