well i bought my hermit crabs my new shells and i left there old ones in the tank and today i noticed at the end of the old shell there was 2 tenicals moving in and out of the end ofthe shell and as i was looking at the rest of the shell there was white spots like the dry salt crystals on the shell and there is black something moving under the crystal looking things and you seel legs coming out under the crystal?????? does any one know what i should do about this ????? is this normal???? 
