A rich microbial ecosystem about twice the size of all the ocean around the world continues to thrive underneath the ground.

An international team of researchers found the underground world teeming with between 15 billion and 23 billion tons of diverse microorganisms. Moreover, the underground world is still mostly untouched and unexplored by humans.

Earth's Secret Underground World

To study the subsurface ecosystem, researchers took samples from boreholes that are more than 5 kilometers deep and from under-the-sea drilling sites. The team used these samples to recreate a model of the rich ecosystem deep within the planet.

The result was astonishing. The researchers revealed that up to 70 percent of the bacteria and archaea on Earth exist in the subsurface where there is extreme heat, extreme pressure, no light, and little nutrition.

Moreover, they found that one organism embedded deep within the ground — found 2.5 kilometers below the surface — has been there for millions of years. It survived by creating methane, which it uses not to reproduce but to repair its broken parts.

The report published by Deep Carbon Observatory gave the underground world the nickname "subterranean Galápagos," named after Galápagos Island, because of its diverse life and the fact that the subsurface has remained mostly untouched. Researchers claim that most of the distinct types of microbes existing in the subsurface remain undiscovered and yet to be characterized. Studying the underground ecosystem could expand the scientific community's perspective of the tree of life.

"Exploring the deep subsurface is akin to exploring the Amazon rainforest," stated Mitch Sogin, co-chair of the Deep Carbon Observatory's community. "There is life everywhere, and everywhere there's an awe-inspiring abundance of unexpected and unusual organisms."

The underground world varies depending on geology and geography. Researchers expect the size of the biosphere to expand in the future.

Beyond Earth's Subsurface

The great diverse life underground that has remained unexplored until now is proof that there are still so much to learn about Earth and life on Earth. Moreover, Robert Hazen, a mineralogist at the Carnegie Institute of Science, believe that the discovery can also be applied in the search for extraterrestrial life.

"We must ask ourselves: if life on Earth can be this different from what experience has led us to expect, then what strangeness might await as we probe for life on other worlds?" Hazen told The Guardian.

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