The mysterious monolith found in the remote Utah desert is being removed by an "unknown party".

A mysterious monolith found in the remote Utah desert was removed by an "unknown party" after its sudden arrival sparked theories left behind by aliens.

The shiny triangular pillar protruding about 12 feet out of the red rocks of southern Utah was discovered last Wednesday by amazed local officials who counted bighorn sheep from the air.

However, the tripartite structure was removed by an "unknown party" on Friday evening, the Utah Bureau of Land Management said in a statement.

However, the BLM said it has not removed the private property structure and will not conduct an investigation as "private property crimes" are administered by the local sheriff's office.

The BLM said in a Facebook post on Saturday, “We have received credible reports that the illegally installed structure known as the 'Monolith' has been removed from the public land of the Bureau of Land Management (BLM) by an unknown party .

& # 39; The BLM did not remove the structure which is considered private property. We do not investigate crimes involving private property handled by the local sheriff's office.

The shiny triangular pillar protruding about 12 feet out of the red rocks of southern Utah was discovered last Wednesday by amazed local officials who counted bighorn sheep from the air

"The structure has received international and national attention and we have received reports that an individual or group removed it on the evening of November 27th."

The Utah Department of Public Security said Monday that crew members found "a metal monolith installed in the ground" but "had no obvious indication of who might have placed the monolith there".

"It is illegal to install structures or art on government-administered public land without a permit, regardless of which planet you are from," the agency warned in an ironic press release on Monday.

The BLM said in a Facebook post on Saturday, "We have received credible reports that the illegally installed structure known as the 'Monolith' has been removed from the public land of the Bureau of Land Management (BLM) by an unknown party . "

News of the discovery quickly went viral online, with many noticing the object's resemblance to the strange alien monoliths that spark leaps in human progress in Kubrick's classic science fiction film "2001: A Space Odyssey".

Curious tourists tracked down the mysterious monolith when a similar version was found to appear in Seattle on New Years Day almost 20 years ago.

All over the world, UFO watchers and conspiracy theorists have been obsessed with the shiny triangular pillar.

Utah: The smooth, tall structure was found on November 18 during a helicopter inspection of bighorn sheep in southeastern Utah

Several adventurous hikers successfully located the monolith on Tuesday and cheerfully climbed the mysterious object and took photos with it, although officials did not disclose its exact location for fear that people might get lost looking for it.

Although the structure was only discovered by authorities this month, Google Earth images show that it has been around since at least 2015 or 2016.

Lieutenant Nick Street, a spokesman for the Department of Public Security, said it was possible the structure had been there for 40, 50 years, maybe even longer.

Officials suspect it might have been built by an artist or big fan of 2001: Space Odyssey – the structure is similar to the machines in Arthur C. Clarke's story (pictured)

“It's the kind of material that doesn't deteriorate with the elements. It can only be a few years old, who knows. There's no real way based on the material it's made of, how long it's actually there, ”he said on Tuesday.

Some pointed to the object's resemblance to the avant-garde work of John McCracken, an American artist who lived in nearby New Mexico for a while and died in 2011.

McCracken was known for his free-standing sculptures in the form of pyramids, cubes or slender plates.

Some observers also pointed to the object's resemblance to the avant-garde work of John McCracken (left), an American artist who lived in nearby New Mexico for some time and died in 2011. He was known for his free-standing sculptures in the form of pyramids, cubes or smooth plates (right)

The monolith most closely resembles McCracken's plank-like sculptures that he exhibited in his exhibition at the David Zwirner Art Gallery in New York.

On Tuesday, a spokeswoman for David Zwirner said it was not one of McCracken's works, but possibly from a fellow artist who pays homage.

However, later in the day, Zwirner made another statement suggesting the piece was indeed McCracken's, meaning it had been lying undetected in the desert for almost a decade.

The monolith was in a red rock bay, but workers withheld details about its exact location to prevent others from endangering themselves and trying to look closer

"The gallery is divided in this regard," said Zwirner. "I think this is definitely from John."

He added, “Who would have known 2020 would be another surprise for us? Just when we thought we'd seen it all. Let's see & # 39;

Explorer David Surber visited the monolith last week and posted the coordinates on Instagram. He found that he was near Lockhart Basin Road near Moab.

He wrote about his disappearance in his Instagram story on Saturday evening: “Apparently the monolith is gone.

I suppose nature returned to its natural state. Something positive for people who want to retire in 2020. & # 39;