Hermit Crab Shell Looks Shiny, Metallic

[TDDredge]

I ordered some shells for my hermit crabs to attempt to minimize murder in the tank. Outside of the tank, the shells look fine, but inside of it, one of them has a kind of shiny streak on it that looks almost metallic. The vendor claims they are unpainted, for hermit crabs. Is this a phenomenon others have seen, or should I try to get the crab out of the shell (one of them quickly moved in) and get rid of it?

 

[Daddy-o]

I think you would rip him in half if you tried to pull it out.

 

[Brandon3152134]

Cut one of them in half and mabye you will be able to tell if they are metallic or painted