Help with my pet hermit crab?

his problem is he has an owner who bought a pet with no research on how said pet should be kept ... you never keep one crab by himself ... hermit travel in large colonies in the wild, so to be ripped from the wild and tons of friends only to be kept in your crappy critter keeper is offensive ... your crab is stressed out and i would not doubt he will stop moving completely ... does the crab have a tank that is 80 degrees in temperature and 80 degrees in humidity ??? if not the right temp and humidity, number one killer of hermit ... you said he is digging in aquarium sand ... is it hermit crab coloured sand (if so change it, that is detrimental to the crab), is it sand castle consistency, is it deep enough he could bury himself completely ??? does he have a hut to hide in during the day ??? are there things to climb on ??? does the crab have access to fresh water and marine water, both that have been dechlorinated ??? if you do not dechlorinate the water it damages their gills and kills them ... a fish tank quality dechlorinater is needed and not anything made for hermit (zoo med and crab worx items should be avoided) ... and all hermit need access to salt water made with marine salt from a fish store and again not anything made by zoo med or crab worx ... has the crab been fed meat, fruit and vegetables on a regular basis ... staple hermit crab food (most including zoo med and crab worx) contain a preservative that will kill ... fish flakes are not appropriate food for hermit ... does the crab have a form of calcium to consume ??? and is there an undertank heater to keep the substrate warm ??? you really should do some research before you bring a living creature home ... and as i said, the only problem here is an impulse shopper without a clue, it is just sad the poor little guy has to die slowly and painfully because someone couldn't type land hermit crab care into a search engine ...