8. The Williams Enigmalith
In 1998, a hiker named John J. Williams noticed a strange metallic protrusion in the dirt. He dug up a strange-looking rock which, upon cleaning, turned out to have a weird electrical component attached to it. The electric device was clearly man-made and somewhat resembled an electrical plug.
The rock has since become a well-known mystery in UFO enthusiast circles. It has featured in UFO Magazine and (according to Williams) Fortean Times, a famed magazine devoted to mysterious phenomena. Williams, an electrical engineer, says the electronic component embedded in the stone has not been glued or welded into the granite. In fact, the rock probably formed around the device.
Many believe that the so-called Williams Enigmalith is a hoax, as Williams refuses to break it (but is willing to sell it for $500,000). Also, the stone device does bear a certain resemblance to heat rocks that are commonly used to keep tropical pet lizards warm. Still, geological analysis has apparently determined that the stone is around 100,000 years old, which (if true) would mean the device inside can’t possibly be of human creation. Williams is confident enough to let anyone research the Enigmalith on three conditions: He must be present, the rock must remain unharmed, and he will not have to pay for the research.