The Stargate skull?
Another great oopart is THE crystal skull discovered in Mayan ruins called "Lubaantun", City of Fallen Stones, in British Honduras, Now called Belize. The skull was discovered in 1924 by Anna Le Guillon Mitchell-Hedges daughter of F.A. Mitchell-Hedges who was in charge of the digs at Lubaantun. The story goes that his daughter, Anna, was exploring inside some ruins thought to have been a temple, when she found the exquisitely carved crystal skull which was then missing the jawbone. The missing jawbone was found three months later, about 25 feet away from where the top part of the skull was found.