Along with chocolate, gold, and astronomy, the Maya civilization was also pretty fond of sacrificing kids. Archeologists have recently been scouring the Maya city of Seibal in present-day Guatemala and discovered these sacrificial rituals were even stranger than previously thought.

During their excavation, as reported in the journal Journal of Field Archaeology, researchers from Ibaraki University in Japan found that many of the children sacrificed to the Gods were buried alongside obsidian, a form of glass created when felsic lava from a volcano cools rapidly.

It’s often a glossy black color, extremely hard, and brittle. This means it's an ideal material with which to make sharp tools and weaponry.

The Maya city of Ceibal was first excavated in the 1960s. It remained a settlement for nearly 2,000 years and is one of the biggest sites found in the sweaty lowland Petexbatun region of Guatemala. It now consists of ruined monumental structures, including plazas, pyramids, carved stone monuments, and homes to the elite.

The four graves date back to the late Middle Preclassic period around 950 BCE and contained a total of 42 obsidian artifacts. One contained the bodies of five children, three of which were younger than one year of age, with each body being placed in the shape of a cross. Alongside them were five pieces of obsidian, one of which was placed centrally in the cross between their bodies. The attention given to this formation suggests it had some kind of ritualistic purpose involving the cosmos. Another grave had two infants, aged between two and four, buried face-to-face with a piece of obsidian placed as an offering, as well jade stones and shellfish beads.

Archeologists have collected over 12,000 obsidian artifacts from this Maya site and other nearby settlements. Nevertheless, it was still a highly valued and rare commodity in the Maya lowlands during this time. Ritual burials with obsidian are also not particularly well-documented.

These new excavations, the researchers claim, show that obsidian played a significant role in ancient Maya cultural practices, most likely for some divine or supernatural purpose. It also undoubtedly brought a sense of exotic rarity, as it must have been imported from the volcanic highlands many miles away.