NASA’s missions to Mars have offered scientists a glimpse at what ancient Mars might have been like. That’s exciting since it could reveal that Mars was once habitable, perhaps billions of years ago. But what if Mars were still habitable today? Believe it or not, it actually might be, and researchers are considering the possibility that the Martian underground still provides conditions suitable for life to not only exist but to thrive.

As Space.com reports, astrobiologists recently discussed the possibility of life on Mars at a scientific conference in New Mexico. The scientists discussed how we might discover such life and how it could have persisted over billions of years.

We already know a lot about the Martian surface. Specifically, we know that conditions are extremely hostile to life, and it’s unlikely that the parts of Mars which we’ve explored with rovers and other hardware could support life over the long term.

However, we still know relatively little about what is going on deep within the planet. It’s possible, some researchers believe, that stable water beneath the unforgiving surface could facilitate conditions for life today. If that’s the case, we might actually be able to find it, though it would require some significant exploration in the form of digging.

“The surface of Mars is a very oxidizing, radiation-heavy environment where liquid water is not really stable for an extended amount of time,” Vlada Stamenković of NASA’s Jet Propulsion Laboratory told attendees. “It’s the worst place to look for life-sites on Mars. Groundwater might be the only habitat for extant life on Mars, if it still exists today.”

There’s still no guarantees, of course, but if we hope to find life on Mars today we’d likely have to focus on features that we can’t see from above, like underground caves. Natural caves formed from ancient lava flows could provide conditions suitable for life, with protection from surface radiation and liquid water.

The Mars 2020 mission doesn’t have any plans to dig, at least not in a way that would lead it to discover an underground Martian cave system, but that doesn’t mean that life isn’t down there waiting for a future mission to stumble upon it.

Mike Wehner has reported on technology and video games for the past decade, covering breaking news and trends in VR, wearables, smartphones, and future tech. Most recently, Mike served as Tech Editor at The Daily Dot, and has been featured in USA Today, Time.com, and countless other web and print outlets. His love of reporting is second only to his gaming addiction.