The better technology gets, the more we’re able to learn about this planet we call home. While some of those things are downright frightening, others – like this one – tend more toward the fascinating end of the scale.

Researchers hav discovered that the innermost layer of Earth’s inner core is a 400-mile-wide solid metal ball – and that it responds to the waves created by earthquakes in an unexpected way.

The resulting paper was published in Nature Communications and posits that this “innermost inner core” was formed after a “significant global event from the past.”

Lead author Thanh-Son Pham, a seismologist at Australian National University, explained more in The Washington Post.

“Clearly, the innermost inner core has something different from the outer layer. We think that the way the atoms are packed in these two regions are slightly different.”

They believe that this new research could help us understand how our magnetic field evolved over time, which was one of the key elements in making Earth hospitable for human life.

This is because the curve of the currents inside the planet help generate our geomagnetic field, which in turn helps protect us from “harmful cosmic radiation.”

“Studying Earth’s center is not just a topic of academic curiosity, but something that sheds light on the very evolution of life on our planet’s surface.”

The innermost inner core has different properties that determine the speed of seismic waves as they pass through, and are different too depending on the direction of travel – a phenomenon called “anisotropy.”