Scientists from the University of Tokyo have found a secret hidden deep in South Africa’s Bushveld Igneous Complex.

Within this rocky area that is famous for its rich and diverse ore deposits – 70% of the world’s platinum, as well as other ores including tin, titanium, chromium, and norite are mined there – the Japanese scientists have been drilling to aid our understanding of the planet’s geological complexities.

The project, which is funded by the International Continental Scientific Drilling programme, allowed the researchers to obtain samples from rocks found deep underground. And one particular 30cm long sample from the core of an underground rock was particularly interesting.

In a study recently published in the academic journal Microbial Ecology, the researchers revealed that, in the centre of the rock – which was  found 15 meters below the Earth’s surface, and is estimated at 2 billion years old – they found pockets of living microbes.

Why was this surprising? Well, until now, scientists did not know that anything could survive inside the confines of such an ancient rock, let alone one that was buried deep within the Earth. In a statement, the University of Tokyo’s Yohey Suzuki – lead author on the project – explained the team’s shock at their discovery:

“We didn’t know if 2-billion-year-old rocks were habitable. Until now, the oldest geological layer in which living microorganisms had been found was a 100-million-year-old deposit beneath the ocean floor, so this is a very exciting discovery. By studying the DNA and genomes of microbes like these, we may be able to understand the evolution of very early life on Earth.”

It was only when analyzing slices of the rock sample that the scientists began to notice something unusual going on.

Since the microbes were quite unexpected, the team had to rule out that the microbes were a result of the extraction process. However, after using three different types of imaging techniques, they were able to identify the microbial cells and the surrounding material and conclude that they had, in fact, been there the whole time.

It was this surrounding material – a tightly packed clay – that the scientists concluded was key to the presence of the microbes in the rock in the first place. Since all the cracks in the rock were filled with clay, the organisms were tightly packed into the core of the rock and trapped there for billions of years.

And most surprisingly, the microbes were still alive.

Since these are the oldest living microbes ever discovered on our planet, their excavation has been something of a turning point for microbiologists and geologists alike. It has also piqued the interest of astronomers, since these ancient rock-dwelling microbes could tell us something about life on our neighboring planets too, as Suzuki noted in the statement:

“I am very interested in the existence of subsurface microbes not only on Earth, but also the potential to find them on other planets.”

The fact that these microbes have survived for so long, evolving very little – if at all – whilst being resilient to all the changes that the last couple billion years have wrought on our planet, tells us a lot about the origins of life.

And even more so, it tells us that our oldest rocks are not only hospitable to our most ancient microbes, but also seemingly allow them to thrive.

Since NASA’s Perseverance Rover is hard at work gathering samples from Martian rocks, it is hoped that similar microbes could be discovered when these samples are analysed, as Suzuki continues:

“While Martian rocks are generally much older (3 billion to 4 billion years old), NASA’s Mars rover Perseverance is currently due to bring back rocks that are a similar age to those we used in this study. Finding microbial life in samples from Earth from 2 billion years ago and being able to accurately confirm their authenticity makes me excited for what we might be able to now find in samples from Mars.”

Though this is mere speculation for now, the team’s unprecedented findings could be just what we need to learn if there really is life in space.

If you thought that was interesting, you might like to read about 50 amazing finds on Google Earth.