Here’s what you’ll learn when you read this story:

Earth’s oxygenated atmosphere and magnetic field make life possible, but scientists have discovered that there’s a hidden link between the two that’s stronger than we originally imagined.

Comparing 540 million years of data from charcoal deposits and magnetic crystals formed from ancient volcanic eruptions, scientists found that the processes creating both increase at the same rate over time, and even experience the same jump in activity levels around 330 million years ago.

Scientists aren’t yet certain which mechanism is impacting the other—or if there is a third mechanism impacting them both.

If you list all of the things that had to go right to make life on Earth possible, our minuscule existence (cosmically speaking) seems all the more amazing. Our Sun is a G-type star with moderate radiation output that doesn’t tidally lock our planet. The Earth is situated in our Sun’s habitable zone. The planet has maintained a robust atmosphere for hundreds of millions of years, and the dynamo at the planet’s heart generates a magnetic field that protects us from the most harmful effects of space radiation. Earth truly is a paradise for life.

Although scientists have known about these life-giving aspects of Earth for centuries, they’re still discovering surprising connections between them. In a new study published last week in the journal Science Advances, scientists from NASA, the University of Washington, and the University of Leeds in the U.K. discovered a surprising connection between two of Earth’s most important life-sustaining features—its oxygenated atmosphere and its magnetic field.

Related Story How Dueling Magnetic Fields Give Us Auroras

It’s hardly surprising that the existence of one of these features might impact the existence of the other. After all, Mars (which is also in the Sun’s habitable zone) used to have an atmosphere, but without a robust magnetic field, the Red Planet eventually lost that atmosphere to the unrelenting lashing of solar winds. However, the authors of this new paper found that, on Earth, the correlation between these two systems runs much deeper than we previously imagined.

“We find that both exhibit strong linearly increasing trends, coupled with a large surge in magnitude between 330 and 220 million years ago,” the authors wrote. “Our findings suggest unexpected strong connections between the geophysical processes in Earth’s deep interior, the surface redox budget, and biogeochemical cycling.”

Analyzing data stretching back to the Cambrian some 541 million years ago, the researchers found that the rise in Earth’s magnetic field and the rise in its oxygen levels were very closely aligned—slowly increasing overtime, except for one bout of increased activity lasting from 330 million to 220 million years ago. To map this comparison over the course of hundreds of millions of years, the researchers couldn’t rely on direct data—there is no such record for atmospheric oxygen levels, for example. However, they could track the strength of wildfires, which show up as charcoal deposits in the geologic record. This would provide a clue, since a stronger, longer-lasting fire means that there was more oxygen in the atmosphere to fuel said fire.

To compare this record with Earth’s magnetic field history, the team analyzed certain magnetic crystals that formed in ancient volcanoes and—due to their composition—essentially act like a “compass frozen in time,” Once plotted side-by-side, the team noticed that the two processes largely increased in lockstep with one another, and even experienced the same increase 330 million years ago. Interestingly, this coincides with the formation of Pangea, though scientists aren’t sure exactly if the formation of the supercontinent is related to the increase or a coincidence, as the data does stretch back far enough to compare levels to other supercontinents in Earth’s history.

Related Story Change in Earth’s Magnetic Field Exposed in Bricks

So, what’s going on here? Well, the researchers aren’t exactly sure, but they have a few guesses. The most likely one is that Earth’s magnetic field directly impacts oxygen levels, as it protects Earth (and oxygen-producing plants) from solar radiation. However, it’s also possible that increased oxygenation coupled with plate tectonics—which drive oxygen toward the liquid outer core that produces the magnetic field—could also play a role. The authors also aren’t ruling out the idea that a third, currently unknown mechanism could provide an explanation for this steadily upward trend.

“One single mind cannot comprehend the whole system of the Earth,” Ravi Kopparapu, a co-author of the study from NASA, told Live Science. “We’re like kids playing with Legos, with each of us having a separate Lego piece. We’re trying to fit all of it together and see what’s the big picture.”

While 540 million years is an unfathomably long time compared to our human lifespan (or even our species’ existence), it’s only around 12 percent of Earth’s entire existence, so these trends could simply be coincidental. All we can do is continue searching for answers among the clues that we do have, and try to grasp just how wondrous our home planet really is.