Researchers at the Vatican Museums in Rome were studying the collection’s nine purported ancient Egyptian full-body mummies, when they discovered that two of the mummies aren’t ancient at all but fakes likely created in the 1800s. That might be pretty embarrassing—if fraudulent Egyptian artifacts weren’t relatively common and often difficult to detect.

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The two mummies in question are small—both less than two feet long, the Telegraph reports—and were once believed to contain the remains of children or possibly falcons. But a series of examinations using advanced technology including X-rays, 3D CAT scans, CT scans, DNA testing and carbon dating have shown that the bones within the wrappings belong to a man and a woman and actually date back to the Middle Ages. Another tale tell sign they’re fakes: scientists also discovered a “modern nail” amidst the bones, reports Catholic News Service.

The mummies’ exterior holds clues to forgery, too, writes the Telegraph:

The three-dimensional painted coverings made of plaster and linen bandages -- called cartonnage -- had a yellowish resin that researchers say is unique to Europe in the mid-19th century, often used in Britain to give antiques a gilded coating.

Interestingly enough, the wrappings that cover the mummies are the only part of the two specimens that date back to ancient Egypt. That’s likely because the 19th century fraudsters responsible for the fakes had access to such authentic materials due to what some refer to as the era’s “mummy mania.”

Napoleon’s expedition to Egypt in 1798, combined with the discovery of the Rosetta Stone in 1799 set off an obsession with Egyptian antiquities amid the wealthier populations in Europe and the United States, writes CNS. Watching the unwrapping ancient remains to discover what was inside became a source of entertainment for some. And those who made the trip back to Egypt often sought to purchase artifacts to show off back home. As CNS points out:

One monk captured the mood when he noted in 1833, "It would be hardly respectable, upon one's return from Egypt, to present oneself without a mummy in one hand and a crocodile in another."

Vatican researchers say that the discovery and examination of the fakes helps them to better understand how to identify forgeries. The work is part of the Vatican Mummy Project, a preservation and research effort launched in 2007 to catalog and conserve the collection’s human specimens.

The research team has also made previous discoveries through the project. In 2013, they found that a mummy previously thought to belong to a woman is actually a man. On another adult mummy, scans revealed a small scalp tumor—the first of its kind to be found on such a specimen.