Austrian farmer named Franz Koglinger went looking for his lost cat when he stumbled upon this 25-foot-deep, perfectly round hole in his field that - as he claimed - appeared overnight.
So naturally, Franz threw a rock down the deep hole and heard a metallic clunk. Next, he tried a magnet, which stuck to something metallic. What could this mysterious hole be all about?
... soon the mystery drew local, national and, finally, international attention. Curiosity-seekers, geologists and UFO buffs flocked to the farm to see the hole for themselves. A buried UFO became a favorite explanation.
There is a perfectly logical solution to this, Neatoramanaut, as Benjamin Radford of Skeptical Inquirer wrote over at Life's Little Mystery, but see if you can come up with an answer first: Link