Archeologists have long known about two unique burial sites in a cemetery in Passo Marinaro in Sicily since the 1980s. They were unique in the sense that the bodies inside the graves were buried with five large stones and amphora fragments, which are part of a ceramic vessel, on top of it. None of the other graves in the cemetery had these.

The reason as to why the bodies in these sites were pinned down with these heavy objects, as if someone wanted to ensure that they remain trapped, remained a mystery. But in a new report published by Carrie Sulosky Weaver on Popular Archeology, she said that the graves were actually that of "revenants" or dead bodies that can re-aminante. In the present times, they would be referred to as zombies.

"To prevent them from departing their graves, revenants must be sufficiently 'killed,' which [was] usually achieved by incineration or dismemberment," said Sulosky Weaver, according to Live Science.

"Alternatively, revenants could be trapped in their graves by being tied, staked, flipped onto their stomachs, buried exceptionally deep or pinned with rocks or other heavy objects," she further wrote.

Sulosky Weaver studied the burial sites for her book, "The Bioarchaeology of Classical Kamarina: Life and Death in Greek Sicily," and thus needed to delve on supernatural practices in the ancient period. She also discovered tablets with magical spells, which could explain the burials. Apparently, people of ancient Greece called the dead for their own gain.

"Usually, the petitioners wanted to gain an advantage in love or business, and it was understood that the deities would direct the spirits of the dead to fulfill the requests of the living. To ensure that the tablets reached the underworld, they would be placed in or near the graves of the recently deceased during secret nighttime ceremonies."

"Some chose to recruit the dead to achieve specific goals, while others chose to trap potentially dangerous bodies in their graves to keep the living members of the community safe," she told Live Science.