Scientists finally solve mystery of strange “golden orb” found 2 miles deep

The unusual golden mass, discovered at a depth of 3,250 meters (over 2 miles) in the Gulf of Alaska, turned out to be the remains of dead tissue from a giant deep-sea anemone called Relicanthus daphneae. Specifically, it was part of the anemone’s base, which anchors the animal to rocky surfaces on the seafloor.

During NOAA Ocean Exploration missions aboard NOAA Ship Okeanos Explorer, encountering unfamiliar organisms is not unusual. In many cases, scientists can quickly identify these finds by sharing knowledge and collaborating. However, some discoveries resist easy answers, and the “golden orb” became one of those rare, lingering mysteries.

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Discovery in the Gulf of Alaska

In 2023, the remotely operated vehicle Deep Discoverer (launched from Okeanos Explorer) was exploring more than 2 miles below the surface in the Gulf of Alaska when it spotted something unusual. Resting on a rock was a rounded, golden object with a small opening, unlike anything the team had seen before.

The discovery raised immediate questions. Could it be an egg case, a sponge, or something entirely new? Some even wondered whether a creature had entered or exited through the opening. The unusual appearance sparked widespread curiosity and speculation.

To investigate further, the team carefully collected the object using a suction sampler and sent it to the Smithsonian National Museum of Natural History (NMNH) for detailed study.

A Complex Investigation Using DNA and Microscopy

Solving the mystery of the “golden orb” took years of careful analysis. Unlike more straightforward identifications, this case required multiple scientific approaches and specialized expertise.

“We work on hundreds of different samples and I suspected that our routine processes would clarify the mystery,” explains Allen Collins, Ph.D, zoologist and director of NOAA Fisheries’ National Systematics Laboratory, which is physically located within the Smithsonian National Museum of Natural History. “But this turned into a special case that required focused efforts and expertise of several different individuals. This was a complex mystery that required morphological, genetic, deep-sea and bioinformatics expertise to solve.”

Researchers from NOAA Fisheries and the Smithsonian used an integrative taxonomic approach, combining physical examination with genetic testing. Early analysis showed that the object did not have typical animal features. Instead, it consisted of fibrous layers packed with cnidocytes (stinging cells), indicating it likely belonged to a cnidarian, the group that includes corals and anemones.

Further study by National Systematics Lab scientist Abigail Reft identified the cells as spirocysts, which are unique to the Hexacorallia subgroup of cnidarians. Scientists also compared the specimen to a similar object collected in 2021 during an expedition aboard Schmidt Ocean Institute’s Research Vessel Falkor, finding matching cellular structures.

Genetic Evidence Confirms the Answer

Initial DNA barcoding attempts did not provide clear results, possibly because the sample contained genetic material from other microscopic organisms. To get a more definitive answer, the team turned to whole-genome sequencing.

This deeper analysis confirmed the presence of animal DNA and revealed a strong genetic match to the giant deep-sea anemone Relicanthus daphneae. Sequencing of mitochondrial genomes from both specimens showed they were nearly identical to a known reference genome for this species.

What the Golden Orb Really Was

With all the evidence combined, scientists concluded that the “golden orb” was not an egg, sponge, or unknown organism. It was a leftover structure from a deep-sea anemone, specifically the base that once attached the animal to the seafloor.

Although this discovery answers the question of the orb’s identity, it also highlights how much remains unknown about life in the deep ocean.

The Deep Ocean Still Holds Many Mysteries

“So often in deep ocean exploration, we find these captivating mysteries, like the ‘golden orb’. With advanced techniques like DNA sequencing, we are able to solve more and more of them,” said CAPT William Mowitt, acting director of NOAA Ocean Exploration. “This is why we keep exploring — to unlock the secrets of the deep and better understand how the ocean and its resources can drive economic growth, strengthen our national security, and sustain our planet.”

Even with this mystery solved, scientists emphasize that the deep sea continues to be one of the least understood environments on Earth, filled with discoveries still waiting to be made.