Locket

A locket is a piece of jewelry that is usually worn on a chain or necklace around a person's neck. It is usually made as two pieces of metal that form a shell which can be opened or closed to contain something small which is considered very valuable to the owner, such as photographs of the wearer and his or her loved one in modern usage of lockets.

In mainstream Smurfs media, Puppy wears a magic locket on his collar that contains "the key to all magic", which only one person is capable of opening it, as all others trying to open it would be zapped by a lightning bolt. In the cartoon show, Baby Smurf is the only one who can safely open the locket. However, the contents of the locket were never shown to the viewers.