It should repair itself, you can give him some eggshell or calcium powder from the petshop sprinkled on his food for extra calcium. i avoid cuttlefish bones they tend to contain salt.

Your GALS shell will probably be a bit uneven after its repaired itself but it wont do him any harm.

__________________

Owned by 3 human children, Kyle, Ebony and Harvey Bob the Chinese Hamster, Jamie the African Pygmy Hedgehog, Bugsy and Nelson the Guinea Pigs, and Stewie, Dora, Jessie and Billy the Bunnies RIP Mr Chip Sleep tight little angel