An African friction oracle

Rubbing this double-headed crocodile sculpture 

can deliver an answer to difficult questions.

From the Metropolitan Museum of Art:

"Regarded as infallible divinatory instruments, friction oracles (itombwa) were used to mediate between diviners and omniscient nature spirits in order to determine the cause of illnesses and appropriate courses of treatment and to expose dishonesty. They performed this role in the guise of an animal form, favored by nature spirits, designed to register their insights in response to human manipulation."

Image is from Discover African Art>>