The Smithsonian Crystal Skull is shown in this undated photo provided by the Smithsonian Institution.

Washington ? Some mysteries are such fun you almost don’t want to know the truth. That may help explain why people are fascinated with crystal skulls.

Happy to share the spotlight with the latest Indiana Jones movie, the Smithsonian’s Museum of Natural History is putting its crystal skull on display starting today.

“People like to believe in something greater than themselves,” Smithsonian anthropologist Jane MacLaren Walsh said, and crystal skulls are mysterious and beautiful.

The skulls “are a fascinating example of artifacts that have made their way into museums with no scientific evidence to prove their rumored pre-Columbian origins,” she added.

Crystals carved into the shape of a human skull fed the 19th century’s need for drama and mystery and its fascination with death. They were supposed to be the creation of ancient Mesoamericans – Aztecs, Mixtecs, Toltecs, perhaps Maya.

The skulls were claimed to represent the art and religion of these peoples. Some even said the skulls had special, even supernatural, powers.

Scientists say it ain’t so.

Nonetheless, the giant crystal skull that mysteriously arrived at the Smithsonian 16 years ago is out of its locked cabinet in Walsh’s office and will be on public view until Sept. 1.

Studying this skull led Walsh to extend her investigation into crystal skulls in other museums and to conclude that all are fakes, made in the 19th and 20th centuries.

“In the past, most carved skulls were assumed to be ancient,” she said. After all, why would someone go to the trouble of faking one?

Still, she is glad it arrived at her doorstep and prompted the study. “This particular object has told us a whole new story,” she said.

The museum’s director, Cristian Samper, said people often ask him if there is a real Indiana Jones doing archaeological work.

“I tell them there are several,” he said. “People doing field work that is every bit as interesting.”

Of the many crystal skulls in museums and private collections around the world, the Smithsonian’s is one of the largest, at 10 inches high and weighing 30 pounds. It was mailed to the museum anonymously, accompanied by a note claiming it was of Aztec origin.

It isn’t, Walsh said.

The skulls were carved from blocks of quartz – sometimes called rock crystal – and show the marks of modern carving tools. That means they were not made before the 19th century. The Smithsonian one, she said, seems to have been made between 1950 and 1960.

Indeed, no crystal skulls have ever been found at an archaeological site.

True, skulls appear in Aztec and Toltec art. But, as scientists point out, they always were carved in relief in basalt, a dark rock.

Scientists think the crystal skulls were made in Europe and Mexico, most in the 19th century, a period when there was a thriving market in antiquities, real and fake.