We seem to have entered something of an alien renaissance. Public interest in extraterrestrial speculation soared this summer, as former intelligence officials testified to Congress that the U.S. government is in possession of materials from a spacecraft of “non-human origin.”

For all its mystery and intrigue, though, this moment is only the latest surge in a century of extraterrestrial hype, and of claims to the existence of alien artifacts. So far none have held up to scrutiny, and it remains to be seen whether the Pentagon is hiding the real deal. But there’s a long list of fascinating (and decidedly not authentic) objects that people have taken to be of alien origin.

Read More: What Does Extraterrestrial Mean, And Why Are Experts Looking for It?

1. Coso Artifact

One winter morning in 1961, the three owners of a rock shop in eastern California went hunting for geodes. Later that day, when they brought their haul back to the shop and started slicing them open, the trio discovered something inexplicable: At the center of one “geode,” where they expected to find an array of sparkling crystals, they saw instead a circular piece of what appeared to be white porcelain surrounding a shaft of metal.

They were baffled. The object seemed man-made, but one of the discoverers claimed to have spoken with a geologist who said the surrounding rock would’ve taken 500,000 years to form. However, as noted in an analysis by Pacific Northwest Skeptics founder Pierre Stromberg and Louisiana State University geologist Paul Heinrich, “very little is known about the initial physical inspections.”

The True Origins of the Coso Artifact

After decades of speculation, Stromberg and Heinrich closed the case with help from a surprisingly niche group of experts — the Spark Plug Collectors of America. Several of its members concurred that the so-called Coso artifact is simply a Champion spark plug from the 1920s, potentially used in a 20th-century mining operation. Nevertheless, it still routinely shows up on lists of “out-of-place artifacts” (OOPArts) as possible evidence of aliens.

Read More: 3 Historic Hoaxes That Duped The Masses, Scientists Or Media

2. Klerksdorp Spheres

Similar to the Coso find, several stone spheres, also known as Ottosdal objects, have been found in 3 billion-year-old geological deposits in Ottosdal, South Africa, just outside of Klerksdorp. A 1979 article in the National Enquirer described them as “so perfectly made that they look as though they were cast from a mould,” and ever since, creationists and ancient astronaut theorists have interpreted them as the artificial products of an advanced civilization.

The True Origins of the Klerksdorp Spheres

Their name, however, is a misnomer. “A careful examination of the Ottosdal objects demonstrates the imaginary nature of the ‘perfectly spherical’ descriptions given by various authors,” states an analysis, also by Heinrich. In reality, the objects come in many shapes and sizes and are mostly asymmetrical. They’re just good old-fashioned carbonate concretions.

Some of the objects feature a series grooves around their circumference. The grooves, Heinrich explains, are merely the result of the sediment layers in which the objects formed: In fine-grained layers they grew more slowly, leaving what seem to be etched rings. The same process can be seen at work in the “Moqui Marbles” of southern Utah.

None of this, of course, prevents vague assertions that the objects may be “connected in some way” to Iapetus, a moon of Saturn that happens to have a similar ridge around its equator. Or that they are “so delicately balanced that, even with modern technology, they would need to have been made in zero gravity.”

Read More: Hollow Earth: A Journey Through 3 Centuries of Conspiracy Theory

3. Quimbaya Treasure

The “Quimbaya Treasure” is an assortment of gold objects created by the Quimbaya culture, which reached its peak in what is now Colombia between 500 B.C.E. and 600 C.E. But of the 135 artifacts in the collection — which include everything from containers and pendants to human and animal figurines — a handful have been singled out as evidence of ancient aircraft (and, by extension, aliens).

The producers of the pseudoscientific TV series Ancient Aliens call them the Tolima jets. They’re shaped a little like birds or insects or fish, but (the producers argue) the anatomy doesn’t add up: Many have what appear to be wings, as well as vertical tails, a perplexing combo. What does have both? Modern fighter jets. Ergo pre-Columbian people must have achieved flight, millennia before Orville and Wilbur Wright, with help from extraterrestrials.

In 1994, two German men even built (substantially altered) model airplanes based on the artifacts to prove that, scaled and motorized, they could have flown. On Ancient Aliens, the producers claim the men “did not add an inch or remove an inch, they just essentially blew the thing into a larger size.” But again, a quick comparison shows the models to be far more aerodynamic than the originals.

The True Origins of the Quimbaya Artifacts

Chris White, who directed the film Ancient Aliens Debunked, notes that most of the Quimbaya artifacts are simply stylized animals. “Because of that,” he writes, “and the fact that the few objects in question also have teeth and eyes, it seems more likely that these were also depicting animals.” It takes little effort to see them as representations of fish, like the sucker-mouth catfish, which Quimbaya natives would’ve been familiar with.

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4. Crystal Skulls

An assemblage of quartz crystals, carved in the likeness of human skulls and allegedly dating to pre-Columbian Mesoamerica, is another favorite of the Ancient Aliens crew. They started turning up left and right in the late 1800s, and museum curators, eager for exotic curiosities, ate them up. But none came from official archaeological excavations, and none had substantiated backstories.

Perhaps the most famous is the “Skull of Doom,” which Anna Mitchell-Hedges, the adopted daughter of British adventurer Frederick Arthur Mitchell-Hedges, claimed to have found while exploring a ruined temple in Belize with her father in 1924. If that were the skull’s true origin, it would be much too finely crafted for the era — the sort of thing the Aztec and Maya civilizations might’ve had otherworldly assistance for.

The True Origins of the Crystal Skulls

When Smithsonian anthropologist Jane MacLaren Walsh examined it in 2007, however, she concluded the technology used in its creation was “decidedly 20th century” (that is, high-speed, diamond-coated rotary tools).

In her book The Man Who Invented Aztec Crystal Skulls, Walsh traces many of the fakes to a single Frenchman named Eugène Boban, who, as a recognized expert on Mexican archaeology, was able to pass them off as genuine artifacts. Still, it’s unclear where they ultimately came from, so, you know, aliens — with equipment strikingly like that of today’s human jewelers.

Read More: The Real Story Behind Aztec Crystal Skulls That Intrigues Many People

5. Congressional Aliens

Lest you think the fountain of phony artifacts has gone dry, here’s a contemporary example, and one of the boldest yet.

For a brief moment in September 2023, Mexico’s Congress became the showroom for a spectacle the likes of which doesn’t often appear in government proceedings: mummified alien remains, and earnest testimony from the controversial, self-proclaimed ufologist who brought them.

Jaime Maussan, a Mexican journalist, presented two tiny, shriveled bodies, which he said had been found in a remote part of Peru in 2017 and dated to about 1,000 years ago. With oblong heads, three-fingered hands, and an eerily humanoid form, they resembled the classic grey aliens, or “greys,” common in extraterrestrial encounter claims (a bit on the nose, as such hoaxes go).

It may come as a surprise to see supposedly alien specimens taken seriously in the halls of legislature, but it’s a testament to our enduring extraterrestrial obsession.

The True Origins of the Congressional Aliens

As with each of the previous hoaxes, the mainstream scientific community scoffed at the proceedings. After all, when Maussan made similar claims in the past, the bodies turned out to be “recently manufactured dolls, which have been covered with a mixture of paper and synthetic glue to stimulate the presence of skin.” If we want an authentic alien artifact, we’ll have to keep waiting.

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