A research team led by the University of Texas at Austin has discovered rare microbial “wrinkle structures” in 180-million-year-old deep-water sediments in Morocco. The find suggests that complex chemosynthetic ecosystems thrived in the dark, high-pressure depths of the ancient ocean, far beyond the reach of sunlight.
The rugged terrain of the Dadès Valley in Morocco’s Central High Atlas Mountains is a geological cathedral, its towering rock faces acting as a vertical library of Earth’s oceanic history. It was here, while trekking through ancient reef systems that existed when this region was submerged under a prehistoric sea, that Dr. Rowan Martindale stumbled upon a discovery that is forcing a recalibration of how scientists hunt for the fingerprints of ancient life.
Martindale, a prominent paleoecologist and geobiologist at the University of Texas at Austin, was not looking for microbial mats. Her team, which included Stéphane Bodin of Aarhus University, was focused on the ecology of ancient reef systems. To reach these formations, the researchers had to traverse extensive layers of turbidites—sedimentary deposits created by massive, gravity-driven underwater debris flows. While these deposits often feature ripple patterns caused by the movement of water, Martindale noticed something anomalous: a delicate, “wrinkled” texture layered directly atop the ripples.
“As we’re walking up these turbidites, I’m looking around and this beautifully rippled bedding plane caught my eye,” Martindale recalled of the moment. “I said, ‘Stéphane, you need to get back here. These are wrinkle structures!'”
In the lexicon of paleontology, wrinkle structures are tiny ridges and pits, often just millimeters across, that serve as “biomarkers.” They represent the ghost of a once-living community—specifically, microbial mats that once carpeted the seafloor. These mats are composed of vast colonies of bacteria and algae that bind the sediment together, creating a resilient skin on the ocean floor. However, finding them in 180-million-year-old rock is statistically improbable.
Historically, wrinkle structures are a hallmark of the Proterozoic Eon, the period before the “Cambrian Explosion” roughly 540 million years ago. Before the rise of complex animals, microbial mats covered the globe. Once animals evolved the ability to burrow, graze, and stir the sediment—a process known as bioturbation—these delicate textures were almost entirely wiped from the fossil record. To find them in the Jurassic period, an era teeming with diverse marine life, is a rarity. To find them in deep-water sediments is, according to existing scientific models, nearly impossible.
The central mystery of the Moroccan find lies in the physics of light. Standard scientific consensus dictates that wrinkle structures are the byproduct of photosynthetic organisms—algae and bacteria that require sunlight to survive. Consequently, these textures are almost exclusively sought in shallow, tidal environments where the sun’s rays can penetrate to the floor.
However, the turbidites in the Dadès Valley were deposited at depths of at least 180 meters. At this level, the ocean enters the “aphotic zone,” a realm of perpetual twilight or total darkness where photosynthesis is physically impossible. This geographical reality presented Martindale with a paradox: the rocks contained the clear signature of life, but not the kind of life that should have been able to exist there.
“Let’s go through every single piece of evidence that we can find to be sure that these are wrinkle structures in turbidites,” Martindale said, noting that such structures “shouldn’t be in this deep-water setting.”
To solve the puzzle, the team conducted a rigorous forensic analysis of the stone. Chemical testing revealed elevated carbon levels directly beneath the wrinkles, a hallmark of biological decay. They then looked toward modern analogs for an explanation. Using footage from remotely operated vehicles (ROVs) exploring the modern deep-sea floor, scientists have observed similar microbial mats forming in the modern era. These modern mats are not powered by the sun, but by chemosynthesis.
Chemosynthetic microbes thrive by harvesting energy from chemical reactions, often utilizing compounds like methane or hydrogen sulfide that seep from the Earth’s crust or are released during the decay of organic matter. In the ancient Moroccan basin, the turbidite flows themselves likely acted as the engine for this ecosystem. These underwater landslides transported massive amounts of organic “fuel” from the shallows into the deep, while simultaneously burying the area in a low-oxygen shroud that deterred larger, sediment-disturbing animals.
During the quiet intervals between these violent debris flows, the chemosynthetic bacteria would colonize the newly deposited silt, weaving their mats across the seafloor and creating the characteristic wrinkles. If a subsequent debris flow buried the mat quickly enough without eroding it, the structure was “snap-frozen” in time, preserved for 180 million years until Martindale’s hike.
This discovery has profound implications for the search for life on other planets, such as Mars or Europa, where surface conditions are hostile and life may be tucked away in dark, chemically rich subterranean or sub-ice environments. If geologists have spent decades ignoring deep-water rocks because they assumed “no light means no microbial signatures,” they may have been overlooking a massive portion of Earth’s—and potentially the universe’s—biological history.
“Wrinkle structures are really important pieces of evidence in the early evolution of life,” Martindale emphasized. By ignoring their possible presence in deep-water settings, she argues, “we might be missing out on a key piece of history of microbial life.”
The team now intends to move the research into the laboratory, attempting to recreate these structures in flume tanks to understand the precise flow conditions required for preservation. The Moroccan “wrinkles” are no longer just a geological curiosity; they are a mandate for scientists to look deeper, darker, and further than they ever thought necessary.
