分类： science

For more than two decades, a 300-million-year-old blob-like fossil from Illinois held a distinctive title in both scientific records and popular science: the earliest known octopus ever discovered. That designation has now been formally stripped away, after a team of paleontologists produced concrete evidence that the fossilized creature was never an octopus at all — and actually belongs to a different branch of the cephalopod family tree.

Discovered in the fossil-rich Mazon Creek deposit, roughly 50 miles southwest of Chicago, the fossil known as *Pohlsepia mazonensis* was first identified as an early octopus by paleontologists in 2000. That finding upended long-held scientific consensus about octopus evolution, pushing back the estimated origin of eight-tentacled cephalopods by more than 200 million years; previously, the oldest confirmed octopus fossil dated back only 90 million years. This massive chronological gap between *Pohlsepia* and the next confirmed octopus fossil left the scientific community with persistent doubts about the original classification.

“It’s a very difficult fossil to interpret,” explained lead researcher Thomas Clements, a zoologist at the University of Reading. “To look at it, it kind of just looks like a white mush. Superficially, if you’re a cephalopod researcher focused on octopuses, it does bear a resemblance to a deep-sea octopus.” The hand-sized fossil, preserved in rock after the creature died in Carboniferous period seas long before dinosaurs evolved, retained few clear distinguishing features that could resolve the debate — until Clements and his research team turned to advanced imaging technology to uncover hidden traits.

To unpack the “mystery of the weird blob,” the team used a synchrotron, a cutting-edge device that accelerates electrons to generate light beams far brighter than the sun, allowing researchers to examine internal structures within the fossil rock without damaging the specimen. What they found inside settled the long-running debate: a ribbon-like structure of teeth called a radula, a shared feature of all mollusks including both octopuses and nautiluses, but with a distinct arrangement that rules out an octopus classification.

While octopuses typically have either seven or nine teeth per row on their radula, the *Pohlsepia* fossil had exactly 11 teeth per row — a tooth pattern that perfectly matches a known fossil nautiloid, *Paleocadmus pohli*, previously recovered from the same Mazon Creek deposit. Nautiluses are shelled cephalopods, distant relatives of octopuses that still exist in modern oceans today. Clements says the original misidentification likely occurred because the creature’s hard shell decomposed before fossilization, leaving only a soft, blob-like impression of the tentacled animal that confused early researchers.

“This has too many teeth, so it can’t be an octopus,” Clements noted. “And that’s how we realize that the world’s oldest octopus is actually a fossil nautilus, not an octopus.”

Following the publication of the team’s findings this week in the peer-reviewed journal *Proceedings of the Royal Society B*, Guinness World Records announced it will update its listings to remove *Pohlsepia mazonensis* from its title as the earliest known octopus. “The scientists have made a fascinating discovery,” said Guinness Managing Editor Adam Millward. “We will be resting the original ‘oldest octopus fossil’ title and look forward to reviewing this new evidence.”

The fossil, named for its original discoverer James Pohl, is currently held in the collection of Chicago’s Field Museum. While the reclassification means the museum has lost its claim to hosting the world’s oldest octopus, Clements says the collection gains an even rarer specimen: the oldest known fossil of a nautilus that preserves soft tissue, a rare find for organisms whose bodies mostly decay over time. “The Field Museum have a small collection of these ancient nautiluses, which I think as a cephalopod worker is probably the best thing ever,” Clements added. The Field Museum has been contacted for comment on the reclassification and has not yet released a public response.

Deep beneath the forested shores of Olkiluoto Island off Finland’s west coast, a decades-long global quest to solve one of nuclear energy’s most intractable problems is about to reach a historic milestone. After 19 years of construction, the Onkalo spent nuclear fuel repository — named for the Finnish word for “cave” — is poised to become the world’s first operational permanent underground facility for isolating dangerous radioactive waste from the biosphere for hundreds of thousands of years.

Descending in an elevator that drops 430 meters (1,411 feet) in mere seconds, visitors enter a sprawling network of man-carved tunnels cut into 1.9-billion-year-old bedrock. This remote site, located just 15 kilometers from the small inland town of Eurajoki and near three of Finland’s five operating nuclear reactors, was selected for its unique geological characteristics. Geologist Tuomas Pere, navigating the tunnel labyrinth, explains that the site’s migmatite-gneiss bedrock offers exceptional stability and extremely low earthquake risk. Most critically, its isolation from population centers creates a natural buffer that makes long-term storage far safer than above-ground temporary facilities.

The 1 billion euro ($1.2 billion) project, overseen by Finnish nuclear waste management firm Posiva, is expected to receive its operating license from national regulators within months. Once operational, the facility will follow a rigorous disposal process: spent radioactive fuel rods will first be sealed in leak-resistant copper canisters at an on-site encapsulation plant using unmanned machinery. The canisters will then be transported deep into the tunnel network, placed in individual boreholes, and surrounded by layers of water-absorbing bentonite clay designed to act as an additional protective buffer. In total, Onkalo will hold 6,500 tons of spent nuclear fuel generated by Finland’s domestic reactors, operating continuously until the 2120s, when the entire facility will be permanently sealed off from the surface.

Posiva communications manager Pasi Tuohimaa frames the facility as the final missing link in making nuclear power a truly sustainable energy source. “For decades, Finnish nuclear companies have been setting aside funds specifically for this project, so the entire cost is covered by the industry, not taxpayers,” he notes. Experts estimate that it will take hundreds of thousands of years for the waste’s radioactivity to decay back to natural background levels — a timeline that far outlasts almost all of humanity’s oldest constructed monuments.

Globally, the need for a permanent solution is urgent. According to 2022 data from the International Atomic Energy Agency, nearly 400,000 tons of spent nuclear fuel has been generated worldwide since the 1950s. Two-thirds of this waste remains in temporary above-ground storage, either in water-filled pools at reactor sites or in dry cask storage facilities, while only one-third has been recycled through a complex separation process. No other permanent underground commercial repository is currently operational around the world. Sweden broke ground on its own permanent facility in Forsmark last year, but it is not expected to open until the late 2030s, while France’s Cigéo project has faced widespread public opposition and has not yet begun construction.

Despite the milestone, experts warn that long-term geologic disposal still carries unavoidable uncertainties. Edwin Lyman, director of nuclear power safety at the U.S.-based Union of Concerned Scientists, notes that while geologic disposal is widely considered the “least bad option” for nuclear waste, unanswered questions remain. “The copper canisters that hold the waste will eventually corrode, and the scientific community does not have a consensus on how quickly that process will occur,” Lyman explains. “The hope is that corrosion will proceed so slowly that most radioactivity will have decayed to safe levels before any breach can occur, but that remains an open question.”

Lyman adds that leaving large stockpiles of spent nuclear fuel above ground carries far greater risks, including vulnerability to sabotage and nuclear proliferation. Over time, the most radioactive components of spent fuel decay, leaving plutonium more accessible to bad actors seeking to build nuclear weapons, especially if reprocessing infrastructure exists. Any risks from a geologic repository, he says, will primarily fall to far future generations, a challenge that has spawned a unique field of research called nuclear semiotics, which focuses on creating warning messages that can be understood by humans 10,000 years or more from now.

To address this need, Austrian artist and researcher Martin Kunze, leading a long-term information preservation project for the OECD Nuclear Energy Agency, has developed a system called the “nuclear message.” Critical information about the repository will be inscribed on large, durable ceramic plates protected by a hardened glazed surface. Kunze proposes burying hundreds of these plates both around the repository site and within the foundations of local settlements to ensure that the warning is not lost to future civilizations, even as languages, cultures, and landscapes change over millennia.

Finnish officials frame the Onkalo project as a reflection of the country’s consistent, long-term approach to nuclear waste policy. A 1994 national law required all radioactive waste generated in Finland to be disposed of within the country’s borders, a commitment environment minister Sari Multala says Finland has upheld unlike many other nations. “When the law passed, some waste was still being exported, but we made the decision to take responsibility for our own waste, and we have stuck to that commitment,” Multala says. She did not rule out the possibility of accepting limited amounts of nuclear waste from other countries in the future, provided that all international regulatory requirements are met.

The project marks a turning point for global nuclear energy, offering a real-world test of whether permanent geologic isolation can solve the nuclear waste problem that has stalled nuclear expansion in many countries for decades.