Feature 66 is a rectangular basin with two arm-like extensions located in the southwestern quadrant of the Miami Circle. Nine smaller holes occur in the bottom and sides of the basin and the arm-like extensions. Limestone cobbles were found along the eastern wall of the main basin. The excavation notes mention the presence of a thin coating of duricrust on the walls of the basin. Materials recovered from the midden include faunal bone, a large quantity of marine shell, a few ceramic sherds, and fragments of limestone.