[header] How to buy a pet hermit crab [title] Look for a healthy crab. [step] Crabs that do not come out of their shells when misted might be ill, and should not be purchased. Likewise, if you see tiny crab limbs scattered about a crab's tank, do not purchase it. 
This is a sign that the crab is stressed and vulnerable to other illnesses. [substeps] Do not obtain crabs that have a musty smell.