HCA: Hermit Crab Association

Hello!
I just got back from Galveston and found out that one of the shells my father snagged happens to still have a resident! I am completely unequipped to care for it and I'd hate for it to suffer :[
It won't come out for a picture but it's a marine species.

Please make sure you put him in some aquarium salt water! They can't survive for long in the open air.