A mysterious silver object found in the Utah desert less than 10 days ago has disappeared. In a statement posted on Facebook, the state’s Bureau of Land Management (BLM) said that the monolith, as it is referred to, had been removed by “an unknown party” some time on Friday evening. The agency added that while the structure was "illegally installed" on public lands, it is seen as private property by authorities. "The BLM did not remove the structure which is considered private property. We do not investigate crimes involving private property which are handled by the local sheriff's office," the statement said. Biologists discovered the monolith from a helicopter during an annual survey of wildlife in the area on November 18. "I'm assuming it's some new wave artist, or somebody who is just a big <em>2001: A Space Odyssey</em> fan," helicopter pilot Bret Hutchings told Utah news station KSL 5 TV at the time. The Utah Department of Public Safety (DPS) released photos and video of the structure to the public, but did not disclose its location. Online sleuths were quick to track down the monolith, however, comparing the publicised photos, old satellite images and online maps to pinpoint its location. Just 48 hours later, visitors had already started to arrive. Among the first to make the journey to the Red Rock Canyon was David Surber, a former US Army infantry officer who shared a video of him inspecting the monolith on site. He found that the object is not magnetic and claimed that it was made of aluminium. He added that it had a hollow centre and was made of pieces riveted together. “Is it solid?,” he says in his Instagram video. “Not solid. Sounds a little like a cardboard box.” Now, people are expressing their disappointment in the monolith’s disappearance. One couple, Riccardo Marino and Sierra Van Meter, decided to pay a visit to the object during a trip from Colorado to California, only to find it was no longer there. They shared their story with local news station KUTV, as well as their theory on who’s behind it. “It was, you know, people who didn’t want it there. They didn't want people entering the desert. It’s obviously causing a lot of attraction,” Marino said. On Instagram, @thespencerowen posted a video showing where the monolith used to be. “It’s gone,” he said. What remains is a metallic triangular plate. Speaking to AP, Owen added: “I was really bummed … It was so pretty and shiny. I wanted to go see it again.”