A geofact (a portmanteau of "geology" and "artifact") is a naturally formed stone formation that is difficult to distinguish from a man-made artifact.
Examples include several purported prominent ancient artifacts, such as the Venus of Berekhat Ram and the Venus of Tan-Tan, are instead thought by many in the archaeological community to be geofacts. Two sites which show an abundance of what are likely geofacts are Calico Early Man Site and the Gulf of Cambay.