On this day in 1961, a trio of mineral hunters searching for geodes made an unlikely discovery: they found what appears to have been a 1920s sparkplug encased in a 500,000-year-old rock.
Wallace Lane, Virginia Maxey, and Mike Mikesell were hunting for minerals in the mountains outside Olancha, California in February 1961 when they found what they thought was a geode they could sell in their gem shop. But when they cut it open, they found not a geode but a shaft of shiny metal encasing a white porcelain object. Upon further investigation, they found that the object was surrounded by a casing and had a tiny spring at one end. It proved to be a 1920s-era Champion spark plug, which had once been widely used in the Ford Model T and Model A engines. Investigators were bewildered. How had a 1920s-era device been encased in a half-million-year-old rock?
Geologists puzzled over the mysterious discovery for months. Theories have abounded attempting to explain how the modern artifact landed in an ancient rock. Some have suggested it is an artifact from an ancient advanced civilisation, like Atlantis. Others have said it is from prehistoric extraterrestrial visitors to Earth. Some theories even suggest that time travelers from the future left the artifact during a visit to the past.
Since then, however, experts have said that the so-called historic and historical anomaly can be explained by known natural processes. An investigation completed by Pierre Stromberg and Paul Heinrich suggests the spark plug became encased in a volume of sedentary rock composed of iron from the rusting spark plug. Iron and steel artifacts typically form iron oxide deposits rapidly as they rust in the ground.
Soon after its discovery, however, the Coso Artifact mysteriously went missing as did its discoverers: Lane died, Mikesell has become untraceable, and Maxey avoids public comment. The Coso Artifact remains a mystery to this day.