When researchers discovered 3,000-year-old mummified corpses in Cladh Hallan, Scotland, they assumed that the mummified remains belonged to two persons.

However, isotopic dating and new DNA experiments have revealed that the parts originate from six different people, leading some to nickname the discovery has “Frankenstein” mummies.

Researchers are not entirely sure why the mismatched body parts were put together, but believe that their placement was deliberate because researchers found that the parts were assembled approximately 600 years after death.

Some researchers have speculated that the parts were arranged to represent the merging of families via marriage and common ancestry.

According to Terry Brown, a professor of biomedical archaeology at the University of Manchester, there were a few things that just didn’t seem quite right when they dug up the bodies: ”the jaw didn’t fit into the rest of the skull,” he said, in addition to their bones being remarkably well-preserved, likely a product of the high-acid, low-oxygen environment of a peat bog, properties that inhibit the growth of bacteria that breaks down organic materials.

Brown tells National Geographic he believes researchers will discover more composite-like bodies on the island. In fact, he said such mummified corpses may have already been discovered but can only be verified by comparing the DNA of various body parts.

“I think you’d have to go back to a time when the rituals were more bizarre,” Brown said of finding similar corpses. “You’d have to go back to the mists of unrecorded time.”