Source: Internet image. (The images in Aztec Art #4 and Chichén Itzá #20 are photographs taken by the author of this online text.)
Comments: This is a pictures of a Chac-mool, which is a stone statue featuring this reclining figure with a bowl on its stomach. The bowl was used by the Maya-Toltecs as a receptacle for heart and other sacrifices. A Chaac (Spanish and English) is the Mayan god of water and rain; Chaac is parallel to the Aztec god Tláloc. Chaac was represented as an old man with a large, curved, up-turned nose or trumpet; he/it carried an axe, which represented thunder and lightening. He/it was also associated with frogs.
Secondary comment: See Dr. Little's in-class presentation/demonstration for a fuller, and more personal, story about his Chac-mool at Chichén Itzá. In his story Chaac and Chac-mool are fused (confused?).