As far as we know, there’s no life that currently exists on Mars. Missions to the Red Planet have yielded tantalizing clues that life may have existed at some point in the past, but no living organisms have ever been spotted by any rover or other hardware humans have sent to Mars.

But Mars is a big place. Despite several rover missions and other trips to the planet we’ve still only barely scratched the surface of the secrets Mars may hold, and there’s still the possibility that life in some form persists there. At least that’s what Michael Finney, a researcher and co-found of The Genome Partnership, believes, and he said as much during a recent conference at UC Berkeley.

As Space.com reports, Finney spoke about the possibility of Martian life still existing on the Red Planet today. Mars, which at one point in its history had huge bodies of water across its surface, could have been teeming with various forms of life that have since been wiped out as the planet lost much of its atmosphere and surface water. If that was indeed the case, Finney believes something likely stuck around for the long haul.

“If Mars had life 4 billion years ago, Mars still has life,” Finney explained. “Nothing has happened on Mars that would’ve wiped out life. So, if there were life on Mars, it may have moved around, it may have gone into hiding a bit, but it’s probably still there,”

It might sound like a stretch, but it’s actually not that hard to believe when you look at some of the more Earth-like regions of Mars. Researchers studying the planet know that it still has quite a bit of ice in its polar areas, and liquid water might not be hard to find during certain times of the Martian year.

On Earth, life can be found in some of the most hostile environments imaginable. Microorganisms, in particular, have a habit of withstanding extreme temperatures and lack of water for long periods of time, and it’s entirely possible that life in some form has adapted to exist beneath the surface of Mars.

Future missions to the planet would be our best chance of proving or disproving that notion, but unfortunately, that means we’ll have to wait a while before we know for sure.