Courtesy of the British Library

Archaeologists frequently dig up strange stone monoliths, and in every corner of the world. The picture above shows a mysterious “millstone,” discovered in the ancient village of Garb El Kefeir, whose ruins stand in the modern state of Palestine. No one knows the purpose of this stone, and academics are frenzied with theories.

Similar are the Aztec Calendar Stone, the Phaistos Disc, the Plain of Jars, and the mystery stone of Lake Winnipesaukee.

One of the most shocking examples is the Qüümbashyo Rock, discovered in the Gobi Desert in 1899. While Mongolia is replete with “deer stones,” the Qüümbashyo Rock is covered in a writing that no linguist can decipher. Indeed, the language is written as a series of dots and dashes, much like Morse code.

The three-foot-tall rock seems to be polished obsidian, but the most remarkable aspect is that the Qüümbashyo Rock raises the temperature of any room it occupies by at least five degrees Fahrenheit. There is no explanation for this, as the specimen does not emanate heat, nor does it seem radioactive.

The rock is currently in storage at the Smithsonian Museum.