In the depths of an obscure catacomb in Sicily, a young girl lies in a glass-topped casket. Her name is Rosalia Lombardo, and she died of pneumonia caused by the Spanish Flu just one week shy of her second birthday in 1920.

Her father was so grief-stricken that he sought the aid of an embalmer and taxidermist to preserve his child. The embalmer, a renowned Sicilian professor of preservation named Alfredo Salafia, then mummified Rosalia Lombardo so perfectly that her internal organs are still intact a century later.

Indeed, it is difficult to gaze upon the tiny body in the glass coffin and not believe that she will awaken at any moment. Her skin is still smooth and porcelain, and her golden hair is neatly tied back with a large silk bow. And most hauntingly, her crystal blue irises are visible underneath her blonde eyelashes.

This facet of her preservation has led to her becoming known as the “blinking mummy” — because some people swear that Rosaria Lombardo’s eyes still open and close throughout the day.

Why Rosalia Lombardo’s Eyes Appear To Open

Rosalia Lombardo’s eyes have fueled Sicilian lore for the past 100 years. She is one of 8,000 mummies in the catacombs underneath the Capuchin convent in  Palermo, Sicily. And of the thousands of visitors who flock to see the blonde-haired girl, many report witnessing her eyes slowly open.

In fact, a video composite of several time-lapse photographs appears to reveal Lombardo opening her eyes by a fraction of an inch.

While this set the internet ablaze with tales of the mummy who could open her eyes, in 2009, Italian paleopathologist Dario Piombino-Mascali debunked the central myth surrounding Rosalia Lombardo.

“It’s an optical illusion produced by the light that filters through the side windows, which during the day is subject to change,” he said in a statement according to ScienceAlert.

Piombino-Mascali made this discovery when he noticed that workers at the museum had moved the mummy’s case, which caused her to shift slightly and allowed him to see her eyelids better than ever before. “They are not completely closed, and indeed they have never been,” he said. So, when the light changes and hits her eyes at different angles, it can appear as though the eyes are opening.

How A Skilled Embalmer Kept Rosalia Lombardo’s Body From Decomposing

Furthermore, Dario Piombino-Mascali also managed to discover the elusive formula that was used for Lombardo’s impeccable preservation.

When Rosalia Lombardo’s embalmer Alfredo Salafia died in 1933, he took the secret formula to the grave. Piombino-Mascali tracked down the embalmer’s living relatives and uncovered a trove of his papers. Among the documents, he stumbled upon a handwritten memoir in which Salafia recorded the chemicals he injected into Rosalia’s body: formalin, zinc salts, alcohol, salicylic acid, and glycerin.

Formalin, now widely used by embalmers, is a mixture of formaldehyde and water that eliminates bacteria. Salafia was among the first to use this chemical for embalming bodies. Alcohol, along with the arid climate in the catacombs, dried Lombardo’s body. Glycerin kept her body from drying out too much, and salicylic acid prevented the growth of fungi.

But the zinc salts, according to Melissa Johnson Williams, executive director of the American Society of Embalmers, were the critical element in retaining her remarkable state of preservation. Zinc, a chemical no longer used by embalmers, essentially petrified her tiny body.

“Zinc gave her rigidity,” Williams told National Geographic. “You could take her out of the casket prop her up, and she would stand by herself.” The embalming procedure was simple, consisting of a single-point injection without any drainage or cavity treatment.

Rosalia Lombardo was one of the last people interred in the  Capuchin catacombs in  Palermo before they closed to new burials. The more than 8,000 burials in the catacombs date back to 1500 and include nobility, members of the clergy, and the city’s bourgeois. But Rosalia’s are by far the most special because of her preservation.

Her father, according to the catacombs’ website, instructed her embalmer to make her “live forever.” And since the catacombs opened up to the public, she has become known as the “world’s most beautiful mummy” and even gained the nickname “Sleeping Beauty of  Palermo.”

Today, Rosalia Lombardo is housed in a new glass case filled with nitrogen designed to protect the remains of this young girl from oxygen, light, and even tourists, who can visit the catacombs for just €3.

“It was designed to block any bacteria or fungi. Thanks to a special film, it also protects the body from the effects of light,” Dario Piombino-Mascali, the paleopathologist, said, according to Gizmodo.

Now, Piombino-Mascali hopes tourists will stop fabricating “totally unfounded stories” about Rosalia Lombardo, the “blinking mummy.”