Hi There,
Hermit crabs only live for like a week without it's shell in the wild. A predator or enemy will be able to take off with it because it doesn't have anything to hide in.
In a crabitat it...
Yes ~~Not for long. Without their shells they are vulnerable. If your hermit crabs comes out of his shell you have to separate him from the others and give him plenty of shell choices.
not long you should try a to find a way to put him back in his shell or he will die. My Hermit crab left his shell and never made it back. In other words: He left the house and never came back...