A second metal monolith that popped up in Romania 4 days ago has also mysteriously disappeared

• A mysterious metal monolith recently found atop a hill in Romania has disappeared.
• The Romanian monolith appeared on Friday, November, 27, the same day a similar one was reported missing in Utah.
• The Utah monolith was discovered on November 18, but vanished nine days later, state officials said.
• The origin of neither monolith is certain, but according to Google Earth maps, the Utah structure was erected some time between August 2015 and October 2016.

The shiny, metal monolith that recently appeared on a Romanian hilltop disappeared Tuesday.

The nine-foot-tall structure "disappeared overnight as quietly as it was erected last week," journalist Robert Iosub, from the Ziar Piatra Neamt newspaper, told Reuters after seeing the structure. "Now all that remains is just a small hole covered by rocky soil."

No one knew where it came from, or who put it near the town of Piatra Neamt four days ago — but the structure appeared on the same day a twin monolith vanished from the Utah desert.

The origin and subsequent disappearance of both monoliths remain a mystery, though a leading theory reported by the New York Times suggests the Utah structure is a work by the US artist John McCracken.

The Utah monolith lived in the desert for years, but the Romanian monolith had a much shorter lifespan

The twin slabs have some differences: the Romanian monolith is mostly covered in interconnected circles, while the Utah monolith appeared smooth. Both seem akin to the giant slab from an iconic scene in Stanley Kubrick's 1968 film, "2001: A Space Odyssey."

It's unclear when the monolith in Romania appeared, though local news outlet Ziar Piatra Neamt reported the discovery on Friday, November 27.

Insider examined Google Earth data and found that the Utah monolith appeared sometime between August 2015 and October 2016, though members of the Utah Division of Wildlife Resources reported their discovery of the slab on November 18.

Equivalent satellite imagery to establish whether the Romanian monolith has been there for long is not available.

There was no obvious indication of who left either the monolith. Utah state officials poked fun at the idea that aliens left behind the structure.

"It is illegal to install structures or art without authorization on federally managed public lands, no matter what planet you're from," the division said in a statement.

Bill Bostock contributed reporting to this story.