CALIFORNIA (REUTERS) - A 10-foot-tall metallic monolith appeared mysteriously atop a Central California mountain this week, then vanished just as suddenly early on Thursday (Dec 3) in what seemed to be a copycat of one that appeared and then vanished in a Utah desert.

"I can't say it's aliens, but it was here and now it's gone," said Terrie Banish, deputy city manager of Atascadero, California, a city of about 30,000 off US Highway 101 near the central coast city of San Luis Obispo.

"It appeared only (Wednesday) and in the middle of the night someone hauled it off," she said.

"It's under investigation by our police department, but it's not been reported stolen."

The 10-foot tall monolith in Utah, found by officials counting bighorn sheep in a remote desert last month, sparked worldwide awe and drew throngs of hikers making pilgrimages to see.

It hearkened to Stanley Kubrick's 1968 film, "2001: A Space Odyssey", based on a novel by Arthur C. Clarke, in which alien monoliths mysteriously appear.

Another shiny metal monolith found last week in Romania's mountainous Neamt county close to an ancient Dacian fortress vanished four days later on Tuesday.

Like the obelisk in Utah, word spread quickly about the Atascadero curiosity, drawing scores of people hiking up the two-mile trail to see, the Atascadero News reported.

But then video posted on social media showed a group of people replacing it with a wooden cross, Banish said.

"At the end of the day, it doesn't seem like extraterrestrials," she said.