It was supposed to be a straightforward expedition: a team of international researchers donning wetsuits, clambering off the Italian coast near an island called Vulcano, and gathering water samples from a bubbling patch of ocean. What they got instead was something entirely unexpected: a new strain of cyanobacteria so round and heavy they nicknamed it “Chonkus.” As discoveries go, this one wasn’t glamorous. It was dense, slimy, and—true to its name—absurdly “chonk.”

But Chonkus, as algae go, has a bit of star power. Unlike most algae that float aimlessly around the ocean, minding their own business, Chonkus has two killer moves: it grows like crazy when there’s plenty of CO₂, and it naturally sinks to the ocean floor. For researchers hunting for ways to capture and bury excess carbon, that makes Chonkus a prime candidate. Just think of it as a heavyweight champion in the ring against climate change. The team that stumbled upon it has detailed the whole adventure in Applied Environmental Microbiology.

“Fat” Algae for the Win

You may be wondering, “How does one stumble upon a miracle algae?” Well, Max Schubert, Ph.D., was asking himself a similar question. Schubert, who worked at Harvard’s Wyss Institute and is now at Align to Innovate, wanted to explore what happens when you give photosynthetic organisms — like algae — a little extra carbon. His reasoning was simple: if oceanic algae struggle to grow because carbon is relatively scarce, then there must be some critters out there thriving in carbon-rich waters, perhaps getting real chunky in the process.

And where better to look than the island of Vulcano, where shallow volcanic vents bubble up loads of CO₂, creating a natural buffet for any algae with an appetite? Schubert and his colleague, Braden Tierney, Ph.D., both Harvard alumni who got to know each other while sharing lab benches at Harvard Medical School, set up an expedition. Tierney secured funding from SeedLabs, assembled a coalition from all corners of science (including universities and labs in the U.S. and Italy), and brought everyone to the CO₂-loaded shores of Vulcano.

There, in a strange microcosm of sunlight and volcanic gas, they found Chonkus. And as if its size wasn’t impressive enough, the bacteria did a neat little trick: it sank. Yes, you read that right. While most algae flit around in the water like harmless sea confetti, Chonkus sank like a miniature green rock to the bottom of its test tube. Schubert likened its behavior to “green peanut butter.” Forget bioengineering; this thing was basically built for industrial-scale decarbonization right out of the box.

Going Big with “The Chonk”

Once they had Chonkus back in the lab, Schubert and Tierney’s team didn’t waste time. They replicated conditions Chonkus would love — warm temperatures, loads of light, and an all-you-can-eat carbon dioxide buffet. Two strains emerged from their culturing efforts, but UTEX 3222 stole the spotlight. Its individual cells were larger than anything Schubert had seen before, earning it the affectionate moniker “Chonkus.” It didn’t just look chunky; it grew chunky, creating densely packed colonies that would make any lab technician swoon with pride.

But beyond its girth, Chonkus had more intriguing traits: it produced large carbon-storage granules in its cells, and it carried a higher carbon content than its skinny relatives. And, of course, it had that sinking quality, which makes it an industrial gem. See, when you’re producing algae for industrial uses, the goal is to concentrate and dry the stuff — a process that can make up 30% of production costs. With Chonkus, gravity does half the work for you.

“Many of the traits we observed in Chonkus aren’t inherently useful in their natural environment, but they’re very useful to humans,” Tierney pointed out. In other words, while ocean algae typically grow at modest densities, Chonkus can reach high-density levels, and at higher temperatures, which are perfect for biomanufacturing. It’s as if nature handed humanity a pre-adapted, no-frills, algae-based solution to carbon sequestration — the Chonk, nature’s carbon capture vessel.

An Algae for the Future

The more they studied Chonkus, the more they realized the possibilities: carbon sequestration, sustainable bioproduction of omega-3 fatty acids, antioxidants, algae-based supplements — all in one single, chubby package. Cyanobacteria, like Chonkus, have the nifty trait of gobbling up carbon from their environment, meaning they can combine the process of carbon capture and biomanufacturing, which is essentially a scientist’s dream combo.

As for Chonkus’s long-term prospects, Schubert and Tierney were anything but idle dreamers. They made samples of UTEX 3222 available through the University of Texas’s Culture Collection of Algae, sharing the bounty with scientists everywhere. Meanwhile, Tierney co-founded The Two Frontiers Project, a non-profit that funds expeditions to discover more microbial oddities in extreme environments — from hot springs in Colorado to coral reefs in the Red Sea. The organization hopes to find more of these natural misfits with traits suited for carbon capture, CO₂ upcycling, and coral ecosystem restoration.

Co-author George Church, an eminent professor at both Harvard and MIT, underscores the responsible approach to deploying such superbugs. “The traits inherent in naturally evolved strains like Chonkus can be game-changing,” he said, “but it’s critical to ‘build the seatbelts before you build the car.’” That means Church’s team is also working on bio-containment strategies, because you don’t want Chonkus sneaking out of a bioreactor and having a party in the local pond.