The official word is that it shows up as a black splotch because the island never existed and was erroneously included on older maps. Others speculate a giant mass of pumice was there at one time, but has since floated elsewhere.
It's been nearly 70 years since whatever crashed in the area made headlines, and many inquiring minds are still searching for the truth. Some have made interesting discoveries, like this individual, who found what appear to be scorch marks.
A number of these odd symbols show up throughout the desert and are often identified as "calibration targets" for planes. What remains unclear is why Nevada in particular seems to need so many of them.
With no significant buildings or fueling apparatus nearby, why a plane would land here is puzzling. Though Arizona is overflowing with abandoned airfields built during the Second World War, this one looks remarkably fresh.
They and structures near them have been dated between 2000 and 8500 years old. While they align with the winter solstice's rising sun, researchers are unclear about what significance the formations hold.