For years, UFO hunters and conspiracy theorists looked at Mars' Medusae Fossae Formation and took it as proof of alien life.

To be fair, these rock formations are extremely bizarre — and its origins have always been somewhat of a mystery even long after its initial discovery. Discovered back in the 1960s by NASA's Mariner spacecraft, the formation stretches near Mars' equator and consists of oddly shaped hills and mesas.

Now, researchers finally discover the likely source of the strange Martian formations: ancient volcanic eruptions, according to a report from the American Geophysical Union.

Formations Came From Volcanoes, Not UFOs

The study, published in the Journal of Geophysical Research, reveals that Medusae Fossae was deposited when explosive volcanic eruptions occurred on Mars over 3 billion years in the past.

Scientists came to this conclusion by examining the formation's density and finding that it's highly porous, which is consistent with deposits from a series of volcanic eruptions. Through the years, erosion has worn down the Medusae Fossae, giving it the strange shapes that often catch the eyes of UFO hunters.

The Medusae Fossae Formation is now the largest known explosive volcanic deposit in the entire solar system. It is around 20 percent as big as continental United States and 100 times bigger than any deposit in the planet.

"This is a massive deposit, not only on a Martian scale, but also in terms of the solar system, because we do not know of any other deposit that is like this," lead author Lujendra Ojha, planetary scientist at Johns Hopkins University, says in a statement.

Other Effects Of The Eruption

The study authors believe that the bizarre rock formations aren't the only permanent effect of the volcanic eruptions billions of years ago. They say that it's possible that the violent eruptions ejected water that rose up to over 4 inches high throughout Mars.

Even more significant are the large amounts of gases that could have been released during the eruptions, the team notes.

Greenhouse gases could have kept the planet's surface warm for liquid water that covered the planet. However, the toxic gases from the explosions would have changed the chemistry of the planet from surface to atmosphere. This enormously affected Mars' potential for supporting life, rendering it virtually inhabitable since then.

However, alien hunters who are looking to Mars need not lose hope. Scientists have also recently discovered possible building blocks of life on Mars, specifically organic matter in rocks that are 3 billion years old. The discovery suggests that the Red Planet could have been home to life in the ancient past.