In Simple Terms
Deep in the Pacific, tiny animals live in cracks in mineral-rich rocks. A new study suggests these rocks are more than a source of valuable metals: they are homes for marine life that may not live in the nearby mud. Removing the rocks for mining could destroy habitats—and wildlife we have barely begun to understand.
Slow-Growing Rocks With Rising Economic Value
Polymetallic nodules form over extraordinarily long periods, taking millions of years to grow. Some are about the size of a softball, and they contain metals such as manganese and copper. Their economic value comes partly from their use in electronics and from their connection to industries expected to need more metals, including batteries and solar panels.
Rising demand has drawn companies’ attention to the ocean floor as a possible source of new mineral resources. But finding a useful material does not, on its own, settle the question of whether it should be mined. A nodule is not separate from its surroundings: it is part of a marine ecosystem. Small organisms may live on it or find shelter in its cracks—refuge that the surrounding mud does not provide. That makes the debate about more than how much metal can be collected. It is also about the consequences of removing ancient, slow-forming habitats.
The issue is especially sensitive because nodules do not grow quickly enough to replace those taken away in the near term. If they are removed from an area, their return is not something that can be expected on a human timescale; forming in the first place takes millions of years. This does not mean that every possible impact is known, or that every area will be affected in the same way. But it does make caution important, particularly when so little is known about the life associated with these rocks.
Hundreds of Samples Reveal Unexpected Residents
The research team focused on hundreds of nodules collected from the Clarion-Clipperton Zone in the Pacific, an area attracting particular interest from companies seeking to mine the deep sea. Examining the samples, the researchers found thousands of microscopic animals living in cracks and cavities in the rocks. On average, each nodule contained 17 animals, while some held hundreds.
The organisms were varied. They included nematode worms and tiny crustaceans, along with other forms of microscopic life. One standout was a single-celled organism the researchers named Thurammina sp. 1. The label sp. 1 marks it as a distinct organism in the study, but the available information does not give it a more specific species name. Its relatively frequent presence among organisms living in nodules underscores that these rocks are more than passing patches of hard surface on the seafloor.
These figures describe what the researchers found in the samples they examined; they should not be treated as a complete census of everything living in the region. An average of 17 animals per nodule does not mean that every nodule contained the same number—some samples held hundreds. And finding thousands of animals across hundreds of nodules shows how extensive the microscopic life associated with them can be, but does not establish the full number of species or how they are distributed across the ocean floor.
The Rock Itself Is a Habitat, Not Just an Object on the Seabed
One important finding was that communities living on nodules or inside their cavities appeared different from those in nearby sediment. A nodule offers a hard structure full of cracks, while the surrounding sediment is a different kind of environment. The organisms collected from each setting also differed noticeably. This supports viewing nodules as habitats in their own right, rather than as isolated rocks scattered across an otherwise uniform seafloor.
Comparisons across long distances provide further evidence. The team found that organisms collected from nodules 1000 kilometers apart—about 621 miles—were more similar to one another than to organisms found in sediment next to the nodules. In other words, the kind of place an organism lived appeared to be strongly linked to the makeup of its community, even when the nodules were far apart geographically.
This observation alone does not prove that every species is unable to live elsewhere. But it raises an important possibility: nodules may be essential to the survival of some species, including Thurammina sp. 1. When similar groups of organisms repeatedly turn up in rocky habitats far apart, yet differ from the communities in the surrounding mud, it is reasonable to suspect that the nodules’ own characteristics matter ecologically. Removing this structure could therefore affect some organisms more severely than simply changing the shape of the seafloor.
Co-author Coral Díaz-Ricio Lorenzo, a postdoctoral researcher at Sorbonne University in France, explains that the pattern becomes clear when samples from distant locations are compared with those from nearby sediment. The finding shifts the discussion from the broad question of what organisms live in the region to a more precise one: which parts of the environment do they depend on? Knowing where species live and how closely they are tied to a particular habitat is essential for assessing what might change if that habitat is removed.
Why Does Deep-Sea Mining Raise Environmental Concerns?
Deep-sea mining involves collecting mineral-rich nodules from the ocean floor. But if the rocks themselves provide homes for organisms that do not find the same conditions in the surrounding sediment, taking them away could remove more than a mineral resource. It could mean losing habitats and reducing populations of organisms that depend on them, including species that have not yet been scientifically described or that remain poorly understood.
The study’s lead author, Sabine Gollner, a researcher at the Royal Netherlands Institute for Sea Research and an honorary professor at the University of Groningen in the Netherlands, warns that commercial mining could cause an irreversible loss of the unique biodiversity associated with nodules. Her warning reflects both the fact that the nodules create a distinctive environment and the extreme slowness with which they form. If organisms that depend on them are lost, the original habitat may not be recoverable quickly, even if mining later stops.
The findings do not mean that the environmental impact of every mining project has already been measured, or that the study has determined the fate of every organism it found. But they show that impact assessments cannot be complete if they count only the minerals extracted or the area of seafloor disturbed. They also need to establish what lives on and inside the nodules, whether those organisms can move to other habitats, and what might happen to nearby communities after the rocks are removed.
Clean-Energy Minerals—and the Hidden Cost
A tension emerges between the drive to secure minerals for technologies such as batteries and solar power and the possibility of damaging marine environments that have received little study. A metal’s importance to a technology does not make the way it is sourced environmentally harmless. At the same time, simply noting that organisms live on nodules is not enough to determine the scale of the likely damage or to justify a single decision for every region. Ecological knowledge needs to inform decisions before activity begins, not after habitats have already been lost.
The limited rules governing the industry make the assessment more complicated. The source article points to a lack of clear rules for carrying out deep-sea mining responsibly, as well as differing positions among countries. During the period covered by the report, the United States under President Donald Trump sought to expand offshore mining to reduce reliance on imported minerals. Elsewhere, Japan was considering mining in its waters, while France called for a ban on the practice.
Germany and Chile also called for a temporary halt, while the Pacific island nations of Palau and Fiji urged a suspension through a temporary moratorium. These differing positions show that the issue is not simply a technical question about how efficiently collection machines can work. It is also a debate about how much risk is acceptable, whether the available knowledge is sufficient, and who is responsible for protecting an environment hidden far below the surface.
In a separate development, Impossible Metals announced that it had tested an autonomous robot using artificial intelligence to retrieve nodules while attempting to avoid disturbing nearby marine life. But a system designed to reduce disruption does not, by itself, prove that removing nodules would have no impact. The new findings raise a question that goes beyond how a rock is collected: if a nodule is a habitat, can that habitat be preserved after the nodule is taken away? And what independent measurements would be enough to show that its inhabitants were unharmed?
What Should We Know Before Making a Decision?
The study provides an important foundation for the debate, but it also opens questions that need further research. Finding organisms in hundreds of samples shows that nodules are inhabited. Yet assessing the level of risk will also require a clearer picture of the exact number of species, how widely each is distributed, and how dependent each is on the rocks. It is also important to distinguish finding an organism in a habitat from proving that it cannot live anywhere else. The study raises the possibility of dependence, but it does not turn every possibility into a settled fact.
Following organisms in and around nodules could help determine whether communities on the rocks remain similar across long distances or vary from place to place. Comparisons among multiple regions could also show how widely the pattern observed in the Clarion-Clipperton Zone applies elsewhere. The source provides no details about findings from other regions, so it would not be justified to assume that every nodule-rich seafloor hosts the same communities.
Management decisions also need to take time seriously. A rocky habitat that took millions of years to form cannot be treated as a resource that renews as quickly as some habitats closer to the surface. Preventing damage, identifying sensitive areas, and gathering enough data before any large-scale activity may therefore matter more than trying to repair damage when it is not even clear whether repair is possible.
The broader lesson is that exploring the ocean floor should not be limited to looking for materials to extract. Nodules that appear to be raw mineral deposits also have ecological value, and they may shelter organisms that have not yet been fully described by science. The more clearly we see that a particular rocky structure supports communities different from those around it, the more important it is to account for that fact in any plan targeting the structure.
The Bottom Line
A study published in Scientific Reports shows that polymetallic nodules in the Clarion-Clipperton Zone are more than stores of manganese, copper, and other metals. Their cracks shelter microscopic life, from nematodes and tiny crustaceans to the single-celled organism Thurammina sp. 1. Each nodule contained an average of 17 animals, and some held hundreds. Samples from nodules 1000 kilometers apart, or 621 miles, showed greater similarity to one another than to organisms living in nearby sediment.
These findings complicate plans for deep-sea mining. Removing rocks that take millions of years to form could mean losing habitats and biodiversity that may be difficult to restore—and perhaps species that have not yet been studied. With demand for minerals rising and countries divided over extraction, decisions need to be preceded by a clearer understanding of the life tied to these nodules. Their ecological value deserves as much serious consideration as their mineral wealth.