Research published in 2020 by Nature Communications involved drilling into the seafloor around 75 meters deep and retrieving sediment samples where microbes persisted despite extreme conditions.

The study, using the drillship JOIDES Resolution, collected sediment cores from up to 6,000 meters below the ocean surface in the South Pacific Ocean, revealing microbial survival in deep, nutrient-poor sediments.

Professor Steven D'Hondt explained that these microbes have likely remained in place for 100 million years, with their growth limited by the scarce energy available in their environment.

The research aims to further understand microbial evolution and the conditions that enable ancient microbes to survive over geological timescales, highlighting potential for life in similar extreme environments elsewhere.

The microbes were not fossilized but living organisms capable of division and growth after lying dormant for tens of millions of years, with up to 99.1% of microbes in 101.5-million-year-old sediment still alive.

Scientists from JAMSTEC have demonstrated that microbes trapped in sediments up to 100 million years old can be revived and grow under laboratory conditions, indicating no apparent age limit for life in the sub-seafloor biosphere.

Deep-sea microbes survive on energy levels millions of times lower than surface microbes, raising intriguing questions about their survival mechanisms in such extreme environments.

Oxygen has been detected in all sediment layers, suggesting that despite slow accumulation, oxygen can penetrate deep into sediments, supporting the survival of oxygen-dependent microbes over millions of years.

These findings challenge previous assumptions about the limits of life in extreme, nutrient-limited environments and suggest that the deep subseafloor could be an ideal place to explore the boundaries of life's resilience.

This discovery broadens our understanding of the deep biosphere, showing that life is more widespread and resilient than previously thought, even in environments like undersea hydrothermal vents.

Laboratory experiments showed that these microbes can multiply actively, with some increasing their populations more than ten thousand times within 68 days, indicating thriving communities.

Yuki Morono initially expressed skepticism but confirmed that microbes of this age can still be active, challenging the previous belief that life only exists within a few meters below the seafloor.

Scientists discovered microorganisms trapped beneath the Pacific Ocean floor for over 100 million years, surviving in nutrient-poor, toxic sediment at nearly 5,700 meters depth.