The Richat Structure is also known as the Eye of the Sahara. The giant circular feature in the desert forms a conspicuous bull's-eye in the otherwise rather featureless expanse of the desert, according to NASA. Many people say the structure, with a diameter of about 30 miles, looks like an outsized fossil. According to a former theory, Richat was a meteorite impact structure because of its high degree of circularity. However, it is now thought to be merely a symmetrical uplift that has been laid bare by erosion.