SALT LAKE CITY (AP) — A mysterious silver monolith that was illegally placed in the Utah desert has disappeared less than 10 days after it was spotted by state wildlife biologists performing a helicopter survey of bighorn sheep. The Bureau of Land Management said it had received credible reports that the three-sided stainless steel structure was removed on Nov. 27. A Colorado man told reporters that he and his girlfriend were driving to the site Friday when they passed a long bed truck with a large object in the back and he joked that it was probably the monolith. They hiked into the location, and the structure was gone. It’s not known who removed it.