Every caregiver knows that it’s important for children to wear a helmet for safety. But throughout history, kids’ helmets have gone through some downright bizarre transformations. In fact in one ancient culture, they were made of other children’s skulls.

Smithsonian Magazine reports that members of Ecuador’s Guangala culture buried their infants in the skulls of older children. Archaeologists discovered the buried infants during an excavation of two 2,100-year-old funerary mounds. The babies were buried around 100 B.C.

Two of the infants’ skeletons were wearing the helmets. One was around 18 months old at death, and the other was between six and nine months old.

“The modified cranium of a second juvenile was placed in a helmet-like fashion around the head of the first, such that the primary individual’s face looked through and out of the cranial vault of the second,” the study’s authors wrote in the journal Latin American Antiquity.

The first baby’s helmet came from a child between the age of four and 12. The second helmet was from a child between two and 12 years old. In both cases, scientists believe the skulls must have still had flesh on them when they were applied.

The scientists’ discovery is the only known example of “using juvenile crania as mortuary headgear,” per the study.

“Not only is it unprecedented, there are still so many questions,” lead author Sara Juengst told Forbes.

Photo Credit: Wikimedia Commons

Yes, there are.

For one thing, researchers aren’t sure what purpose the helmets served. They may have been used for protection while the babies were alive, or they may have been part of a burial ritual for protection in the afterlife. According to one theory, they may have belonged to the infants’ ancestors.

But as this was millennia ago, we may not ever know anything more than that the babies were buried in child helmets .