Some 30 miles south of the Tayma oasis in Saudi Arabia stands a strange rock formation called Al Naslaa. Each balanced on a natural pedestal of sand, two large rocks rise above the desert—or what used to be a single, massive block of sandstone, split down the middle. The split is a narrow, clean slit, known as a “joint” in geology. Due to its laser precision, some conspiracy theorists have suspected advanced ancient technology, or even extraterrestrial involvement. But it’s a perfectly natural occurrence, even if it’s not common. The…