SSSHHH! No, you weren't seeing things...Hey, mister shopkeeper dude, whats this necklace thingy?
Shopkeeper: That is not just a "necklace thingy." First of all, we are not alone. There are all kinds of monsters hiding among us. Some of them have human forms which allow them to blend in with the rest of us. That is a special talisman that will force a monster into its true form. Really rare, really valuable.
But...you have a whole a rack of them...
Shopkeeper: Fine, if you want the thing, 5 bucks. No one believes that mumbo jumbo anyway. Can I interest you in a book about cryptozoology to go with it?