Note: Although this is a 19th Cent. tray, it's unusual form suggests that it may not be a divination tray and possibly not even Yoruba.
Divination (Ifa) is practiced to explain misfortunes and help to prevent them. In western Africa, the Yoruba people of Nigeria and Benin use a decorated tray for divination. This round, rectangular, or half-moon-shaped board is carved with geometric and anima motifs and one or more images of Eshu, the Yoruba trickster deity, who is thought to deliver messages to and from the spirit world. The divining process begins by covering the board with white chalk. The diviner then throws palm nuts onto the board and interprets the markings they make on its surface.