The Mitchell Hedges Skull of Doom

The British Museum studied several crystal skulls in 1996 and determined that they were all probably made in Germany within the past 150 years. This explains how they were made with tools unavailable to ancient Mesoamerican peoples at the time. The genuine ancient objects would show haphazard very, very tiny scratches and abrasion. So they're beautiful works of art, but they're not earth shattering evidence of any lost civilization other than our own.