On a laboratory table, far away from the solid darkness of the Gulf of Alaska, that thing still seemed out of place. A golden mass, smooth, almost ordered in its strangeness, arrived from the abyss bearing all the air of objects that waste scientists’ time and gain the imagination of those who look at it. In 2023 it was nicknamed the “golden egg” because, seen on the seabed, it really had something suspended: a small brilliant sphere, attached to the rock, with a hole in the side and no desire to be classified quickly.
Now that name remains good for titles and for memory, but the explanation is much less science fiction and much more interesting. The Alaskan golden egg was a biological residue: part of the base of a large deep sea anemone, Relicanthus daphneae, a creature of the deep capable of living where sunlight reaches only as a concept, crushed by enormous pressures and a cold that leaves very little room for tropical aquarium images. The 2023 NOAA Ocean Exploration expedition found the mass in deep water near Alaska, and after recovery, the sample was sent to NOAA Fisheries’ National Systematics Laboratory, housed at the Smithsonian National Museum of Natural History in Washington. There the answer came: that sphere had been a portion of the base of the anemone, the part with which the animal anchors itself to the seabed.
The golden sphere found in the depths of Alaska has resisted easy answers
The opening scene had all the right ingredients to go viral. The Deep Discoverer remote-controlled underwater vehicle, engaged in the Seascape Alaska 5 mission on board the Okeanos Explorer ship, was exploring the seabed at approximately 3,250 meters of depth. A golden-yellow mass appeared in front of the cameras, about ten centimeters large, adhering to a rock. An object small enough to fit in your hand, strange enough to block a live scientific conversation. The first hypotheses ran where they normally ran: a mass of eggs, a sponge, perhaps a microbial biofilm, perhaps the remnant of something already dead. The sample was carefully collected by the ROV and taken out of that darkness.
The problem came soon after. In cases like this, observation under the microscope, comparison with other samples, some targeted genetic analysis are often enough and the mystery is resolved. Here the ordinary procedure began to stumble. The sphere of the Alaskan golden egg had a fibrous structure, without an animal anatomy readable at first glance. No recognizable body, no form that would allow one to calmly say “here, it belongs to this group”. Yet inside that material there were very specific cells: cnidocytes, the stinging cells typical of cnidarians, the large group that includes corals, jellyfish and anemones. A small, technical, decisive clue.
The spirocysts, specialized cells present in hexacorals, the group which also includes several sea anemones, narrowed the field even further. From there the sample stopped looking like an alien object and started behaving like a piece of marine life left behind. The genetic part, however, took longer. Initial DNA analyzes returned confusing signals, because the material was full of mixed biological traces, microorganisms and environmental residues. In such a deep area, an abandoned structure can immediately become a small table for other invisible life.
The breakthrough came with more heavy lifting: in-depth genomic sequencing, comparison with another similar sample collected in 2021, and analysis of mitochondrial DNA. At that point the identity began to fit together strongly: Relicanthus daphneae. The scientific preprint dedicated to the case speaks of an integrated approach, with morphological observation, genomic characterization, presence of spirocysts and genetic material attributable to this deep sea anemone. The same work also reports similar cuticles observed under living individuals, a detail that makes the explanation more robust and less episodic.
Relicanthus daphneae, the giant anemone that leaves a kind of golden imprint on the seabed
Relicanthus daphneae has little of the tender anemone of domestic imagery. It lives in the abyss, can have a pinkish cylindrical body and very long tentacles, even over two meters according to the available descriptions. Its base, however, normally remains hidden under the animal, glued to the rock or other seabed supports. And it is precisely there that the story becomes more concrete: the anemones attach themselves to the substrate by secreting adhesive and stratified material. Layer after layer, that base can become a kind of biological fingerprint. If the animal moves, dies, or leaves some of its tissue behind, what remains can look completely different from the living organism.
The golden sphere, therefore, would be a residual cuticle, a basal portion, a kind of skin or casing left in place. Scholars hypothesize that it may have detached itself during the animal’s movement, or that it is linked to reproductive processes that are still unclear. Some anemones can also reproduce by leaving parts of the base, from which new individuals develop; for Relicanthus daphneae this remains a possibility to be verified with caution. The cleanest explanation, for now, is this: the sphere was the material sign of a giant anemone, the remnant of its grip on the seabed.
The almost ironic part is that the most conspicuous object was precisely the one that usually remains invisible. The tentacles, the body, the living form of the anemone attract the eye when the ROV illuminates them. The base, however, is below. Work in silence. It keeps the animal attached to the rock, anchoring it to an environment where every centimeter of stability counts. When that base remains alone, it changes role: from a hidden structure it becomes an exhibit, from a support it becomes an enigma.
There is also another interesting detail, less spectacular and more profound. A cuticle abandoned in the depths can become a small hotspot of microbial activity. Microorganisms find organic material, colonize it, transform it. In an environment poor in immediate resources, even a residue left by an anemone can become space, food, passage of matter. The Alaskan golden egg seemed like an isolated object; instead it tells of a network of tiny relationships, much denser than the initial image suggests.
Because such a small mystery says a lot about the depths that we still know poorly
The Seascape Alaska 5 mission had a broad goal: to map, explore, and describe ecologically and economically important deep-sea habitats in poorly understood areas of Alaska. 19 ROV dives were conducted between August and September 2023, to depths ranging from 253 to 4,262 metres, with dozens of biological, geological and water samples collected during the operations. Within this body of work, a golden sphere the size of a softball ended up occupying a place of its own.
The reason is simple: the abyss continues to behave like an archive with many pages still glued together. Every time an ROV illuminates a rock face, an underwater canyon or a submerged mountain, it brings to the surface images that biology has yet to sort into its own categories. Sometimes these are new species. Other times, as in this case, of pieces of already known organisms that no one had observed in that shape, in that position, with that clarity.
The Alaska golden egg case also shows how valuable physical samples are. The images sparked curiosity, but alone they would have left everything in the realm of hypotheses. The collection of the material, the analysis under the microscope, the comparison with other specimens, the sequencing of the genome have transformed a visual oddity into biological data. Without that passage, the sphere would have remained a beautiful photograph from the abyss, good for suggestions and little else.
The answer, however, still leaves some margins open. Scientists have clarified which organism that mass belonged to, and that matters. It remains to be better understood why that cuticle had exactly that shape, whether it was linked to a movement, a death, an incomplete reproductive attempt or an even different process. In marine biology, especially at three thousand meters of depth, solving a mystery often means opening a more precise one.
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