Scientists have just made a big new discovery. How big? It could totally alter our understand of what Mars looked like eons ago.

A research at Los Alamos National Laboratory in New Mexico has published a study this week in the journal Geophysical Research Letters that argues that the recent discovery by NASA’s Curiosity rover of manganese oxide indicates that the planet was once very much like Earth, according to a NASA statement.

Today, Mars is a barren wasteland covered in red rock with only traces of the water that was once here. But the presence of manganese oxide, which only forms in conditions that are wet and oxygen rich, suggests that Mars looked very different billions of years ago.

At some point in Mars’ history, the planet started losing its atmosphere and thus its ability to retain water, but when? And how fast did it start to thin? The latest studies are placing some limits, which is helping scientists narrow down that question.

Scientists have long suspected that the Martian surface was once more Earth-like, as today’s Mars has features on it that could only form in the presence of large bodies of water.

“The only ways on Earth that we know how to make these manganese materials involve atmospheric oxygen or microbes,” said Nina Lanza, a planetary scientist at Los Alamos National Laboratory in New Mexico. “Now we’re seeing manganese oxides on Mars, and we’re wondering how the heck these could have formed?”

Lanza added, “It’s hard to confirm whether this scenario for Martian atmospheric oxygen actually occurred. But it’s important to note that this idea represents a departure in our understanding for how planetary atmospheres might become oxygenated.”