Scientists Discover Unexpected Ancient Life in Deep Ocean Rocks

A Discovery That Defied All Expectations

Dr. Rowan Martindale was walking through Morocco's rugged Dadès Valley when she spotted something that made her stop dead in her tracks. As we're walking up these turbidites, I'm looking around and this beautifully rippled bedding plane caught my eye , the University of Texas at Austin paleoecologist recalls. What she saw were distinctive wrinkled patterns etched into 180-million-year-old rock formations—patterns that, by all scientific understanding, shouldn't have existed in that environment.

Wrinkle structures are millimeter- to centimeter-scale ridges and pits that can form on sandy beds when algal and microbial communities form mats or aggregates. Wrinkles are usually obliterated by animal activity, and so they're rare in rocks younger than 540 million years ago, when there was an explosion of animal evolution. Today, wrinkle structures are commonly found in shallow tidal areas where photosynthetic algae thrive. But these rocks told a different story entirely.

But the turbidites Martindale was walking across were deposited too deep in the water for light to reach, at least 180 meters below the surface, meaning the wrinkles could not have been made by the same type of algae that form them today. Additionally, the rocks were only about 180 million years old, when animals were tearing up the delicate seafloor all over the world. By all accounts, the wrinkle structures should not have been there.

Unraveling the Mystery

Determined to solve this geological puzzle, Martindale and her international team embarked on rigorous analysis. Let's go through every single piece of evidence that we can find to be sure that these are wrinkle structures in turbidites , she decided, knowing that wrinkle structures shouldn't be in this deep-water setting .

Their investigation revealed compelling evidence. Analysis revealed the layers just below the wrinkles contained elevated levels of carbon - a signature of biotic origin. Furthermore, videos from remotely operated submersibles taken of the seafloor well below the photic zone showed that microbial mats could form from chemosynthetic bacteria - bacteria that get energy from chemical reactions rather than light.

The team discovered that the turbidites bring nutrients and organic matter with them, reducing oxygen levels and creating conditions ripe for chemosynthetic life. Then, in the calm periods between turbidite deposition, those bacteria form mats atop the sediment that subsequently wrinkle into the distinctive texture Martindale observed in Morocco. Usually, the next turbidite erodes away the mat, but every once in a while, the mats and their wrinkles are preserved.

Rewriting Scientific Understanding

This discovery, published in the journal Geology, fundamentally challenges how scientists think about ancient life. Previously, wrinkle structures were almost exclusively associated with shallow-water environments where sunlight-dependent organisms could thrive. The Morocco findings prove that similar patterns can form in the deep ocean through entirely different biological processes.

Wrinkle structures are really important pieces of evidence in the early evolution of life , Martindale explains. By ignoring their possible presence in turbidites, we might be missing out on a key piece of history of microbial life .

The implications extend far beyond Morocco's mountains. She also hopes that these findings spur other researchers to incorporate chemosynthetic mats in a paradigm that previously included only a photosynthetic mat origin for wrinkle structures. Then geologists could look for wrinkle structures in new places that were previously written off as fruitless settings in the search for early life on Earth.

Opening New Frontiers

This breakthrough opens entirely new avenues for understanding life's history on Earth. Scientists may now search for evidence of ancient chemosynthetic communities in deep-water deposits worldwide, potentially uncovering a hidden chapter of early life that thrived without sunlight in Earth's ancient oceans.

The discovery also has implications for astrobiology, as chemosynthetic life forms the basis for ecosystems around deep-sea hydrothermal vents today and could represent the type of life that might exist on other worlds where sunlight is scarce. Martindale's accidental find in Morocco's dramatic landscape may have just expanded our understanding of where life can flourish—both on Earth and potentially beyond.