A process to extract metals from their ore with hydrogen could make deep-sea mining for valuable materials more sustainable than mining on land, a new study claims.

Swathes of the ocean floor are littered with nodules the size of tennis balls. These polymetallic nodules are comprised largely of manganese, with smaller amounts of nickel, copper and cobalt, as well as other elements. As the construction of solar power and electric vehicles booms, demand for these metals is increasing because they are vital components of batteries and wiring. But plans to mine for the polymetallic nodules are highly controversial because operations to collect them would potentially harm the deep-sea floor – one of the last pristine ecosystems on Earth.

Even so, some researchers suspect that deep-sea extraction will eventually take place. “I think there is a good chance that someday people… will mine the nodules,” says at the Max Planck Institute for Sustainable Materials in Germany. “So better to have a good process [for extracting metals] after mining than to have one more dirty process.”

, a Canadian deep-sea mining company that has applied for a deep-sea mining permit from the Trump administration, to extract metals using a fossil fuel-based approach involving coke and methane. Its process involves placing the nodules first in a kiln and then an electric arc furnace – a greener alternative to a traditional blast furnace. Even so, the company says its approach will produce 4.9 kilograms of carbon dioxide emissions for every 1 kilogram of valuable metals.

Manzoor and his colleagues have found a way to lower these extraction-related emissions. Their system doesn’t involve a kiln. Instead, the nodules would be ground into smaller pellets and placed straight into an arc furnace that also contains hydrogen and argon gas. High-energy electrons flowing from an electrode in the furnace to the pellets would knock electrons off the molecules of hydrogen gas, forming a plasma that can be heated up to temperatures exceeding 1700°C.

The hydrogen ions in the plasma then react with the oxygen in the pellets, stripping the oxides away from the alloy and leaving pure metal behind. Besides water, the only by-products are manganese compounds that can be used for making batteries and steel.

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If the hydrogen gas used in the furnace is “green” – meaning it is produced by splitting water with electricity from renewable sources – and the electricity to run the furnace is generated from renewable sources, the process should emit no CO2, according to the researchers. Today, the vast majority of hydrogen is produced using fossil fuels.

Metals like manganese are found on land as well as on the seafloor, but at concentrations about 10 times lower. Mining them on land involves moving large amounts of earth, and extracting the metal from the ore often relies on sulphuric acid. The process can result in razed rainforests and polluted rivers.

However, land-based mining could be better regulated to prevent environmental destruction, and the smelting of the metals could be done with green hydrogen and renewable electricity rather than fossil fuels, argues at Pforzheim University in Germany. At that point, vacuuming up nodules from the seabed wouldn’t necessarily be more sustainable.

“We do not see any fundamental advantage for deep-sea mining in terms of carbon footprint,” he says. “The sustainability of deep-sea mining fails because of the threat it poses to the biodiversity of deep-sea flora and fauna.”

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But the process that Manzoor and his colleagues have developed could help deep-sea mining become more economically viable, according to at Imperial College London.

“In addressing how you would do the extraction metallurgy downstream of actually picking it up off the seabed, you may be able to then open up the business case and the environmental case to make that attractive,” he says.

Manzoor stresses that the research isn’t meant to advocate for deep-sea mining, and the environmental impacts should be fully investigated.

Spider-like creatures living near methane seeps on the seafloor appear to cultivate and consume microbial species on their bodies that feed on the energy-rich gas. This expands the set of organisms known to rely on symbiotic relationships with microbes to live in these otherworldly environments.

at Occidental College in California and her colleagues collected sea spiders – marine arthropods named for their resemblance to arachnids – living near three different methane seeps in the Pacific Ocean. They found three previously unknown species from the sea spider genus Sericosura that appear to be abundant only near these gas seeps.

Other types of sea spiders that don’t live near seeps largely eat other invertebrates. But the researchers found the new sea spiders appear to get most of their nutrition by eating a distinctive set of bacterial species that live on their bodies. These bacteria harvest energy by metabolising methane and methanol coming from the seeps, energy that would otherwise be inaccessible to the sea spiders.

The researchers found the bacteria were confined to the spiders’ exoskeletons like a “microbial fur coat”, growing in what Goffredi describes as “volcano-like” clusters. The layers of bacterial growth also had markings like lawnmower tracks where the spiders may have munched on them using their hard “lips” and three tiny teeth.

To confirm the sea spiders really were eating the bacteria, the researchers also used a radioactive labelling technique to track how the carbon in methane was consumed by the sea spiders in the lab. “We watched that methane go into the microbes that are on the surface of the spiders, and then we watched that carbon molecule move into the tissues of the spider,” says Goffredi.

The researchers don’t think the sea spiders are just eating whatever happens to grow on their exoskeletons. Because the species that live on the exoskeletons are distinct from what’s generally found in the environment, it suggests some kind of selection process is at play, says Goffredi. “The spiders are definitely cultivating and farming a very special type of community.”

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Sea spiders wouldn’t be the first organisms to farm microbes to access chemical energy. “Each time we look [at ecosystems around methane seeps], we’re finding this more and more,” says at Temple University in Pennsylvania. He worked with Goffredi on an that found a similar symbiosis in tube worms. The abundance of life found near the seeps “is being fuelled by methane and other chemicals and not by the energy of the sun. That’s pretty amazing,” he says.

Cordes points out that the bacteria also stand to gain by riding along on the sea spiders’ bodies. Not unlike cows on a ranch, they gain protection and access to better pastures. For instance, if a methane seep shifts to a different part of the seafloor, the sea spiders could move the bacteria to the new source. “The sea spiders are keeping them in the perfect habitat,” he says.

A colossal squid — the largest invertebrate on the planet — has been filmed alive in its wild habitat for the first time.

For decades, the Kraken-like colossal squid () was more myth than reality: scientists had only a vague sense of its appearance from fragments of its remains found in the stomachs of the whales that eat the molluscs. In fact, it was through those remains that the species was officially described by zoologists in 1925.

Finally, in 1981, fishers in Antarctica accidentally reeled up a live colossal squid in their fishing nets. Since then, the animals have sometimes been killed as fishing bycatch, or have washed ashore dead.

Last month, a vessel from the , a US-based non-profit organisation, was surveying the Southern Ocean near the South Sandwich Islands and live-streaming the footage from their remotely controlled deep-sea cameras, when an online viewer flagged that they might have just filmed a colossal squid.

Acting on the tip, the researchers sent the high-resolution footage to independent squid experts. The experts confirmed that the online viewer’s hunch was correct: the squid had distinctive hooks along the suckers on its eight arms, which are a hallmark of the colossal squid. It was roaming at 600 metres under the water’s surface.

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While colossal squids are thought to grow up to 7 metres in length and 500 kilograms in weight, the squid caught on camera was a mere 30 centimetres in length: a baby.

“It’s amazing that every time we go down into the deep sea, we find something new and exciting,” says of the Schmidt Ocean Institute.

A colossal squid in its natural habitat in 2023 by researchers from another US-based organisation, – but the sighting couldn’t be confirmed because the footage was too low in quality. The new squid recording might suggest the 2023 footage really does capture a colossal squid. “It’s the same size, same colour, similar depths, both in the Southern Ocean,” says at Kolossal, who is still awaiting further confirmation.

However, there is as yet no footage of an adult colossal squid in the wild, and the lives of these gigantic invertebrates are still mysterious, says , formerly at Auckland University of Technology, New Zealand, who coined the name “colossal squid” in the early 2000s. He once touted the animals as “seriously evil denizens of the deep” but is now convinced they are more like “giant gelatinous ticks, simply blobbing around in the water column near the seabed”.