The Coro artifact (500,000 year old spark plug)

The Coro artifact was unearthed in the Coso Mountains, California, while looking for unusual rocks. One of these pieces of rock contained inside remains of some kind of device. Beneath the outer layer of hardened clay, pebbles and fossil inclusions was a hexagonal shaped layer of a substance resembling wood, softer than agate or jasper. This layer formed a casing around a three-quarter inch wide cylinder made of solid white porcelain or ceramic, and in the center of the cylinder is a two millimeter shaft of shiny metal core, about .08 inch (2 millimeters) in diameter. Also, surrounding the ceramic cylinder are rings of copper, mostly corroded. Embedded too in the rock, though separate from the cylinder, are two more man-made items – what look like a nail and a washer. The rock, in which the artifact resembling a spark plug was found, was dated to about 500,000 year old. Those who manufactured this artifact had to possess an advanced technology.