A tiny golden blob sitting on the ocean floor two miles below the surface, with a hole punched through its center and adhered to a rock as if it had been placed there on purpose, has an almost unsettling quality. During NOAA’s Seascape Alaska 5 expedition in the Gulf of Alaska in 2023, the remotely operated vehicle Deep Discoverer came across exactly that, and for over two years, no one was able to identify it.
Scientists who were watching the video in real time were genuinely unsure. Was it a case of eggs? A lifeless sponge? A microbial mat of some sort? A small, golden, mound-shaped object became one of the most bizarre mysteries the deep ocean had created in recent memory as a result of the conjecture that ensued, which went beyond simple office gossip and attracted public attention. “Everyone was like, ‘What the heck? What is that?'” Smithsonian National Museum of Natural History zoologist Allen Collins recalled in an interview with Live Science. Trained scientists who have devoted their careers to studying strange deep-sea organisms rarely have this kind of response.
A suction sampler was used to gather the orb, which was then sent to the Smithsonian for analysis. What came next was not a fast identification. This case progressed slowly and obstinately in a world where answers seem to come in a matter of seconds. Collins subsequently stated that at first, he thought standard laboratory procedures would resolve the issue. They didn’t. The object lacked any features that would instantly identify it as a specific kind of animal, such as a mouth and visible muscles. It looked biological but offered no easy entry points.
Things became more fascinating when viewed under a microscope. Nematocysts, the stinging cells that characterize the Cnidaria phylum, which includes jellyfish, corals, sea anemones, and over 11,000 other aquatic species, were found in the tissue. They were, more precisely, spirocysts, a type of cell unique to the Hexacorallia class. This reduced it to about 4,000 species. It’s still a big field.
Before genetic testing made things clearer, it made them more complicated. Unsurprisingly for something that had been sitting on the ocean floor, the initial DNA barcoding revealed a jumbled mixture of microbial material, but it also indicated the presence of Relicanthus daphneae, an organism that resembled an anemone. Similar traits were seen in a second specimen that was gathered in 2021 while on a Schmidt Ocean Institute expedition. Animal DNA was eventually verified by whole-genome sequencing, and mitochondrial analysis revealed that both specimens were almost identical to a reference genome of R. daphneae. Slowly, the case was growing.
After years of researching R. daphneae, Estefanía Rodríguez, curator of marine invertebrates at the American Museum of Natural History, contributed the last piece. She identified the tissue as a cuticle, which is the structure that a massive deep-sea anemone secretes underneath itself in order to cling to rocks. The golden sphere wasn’t an egg. Not a sponge. Nothing dramatic or extraterrestrial. It was the calcified base of an anemone that had long since perished, leaving a fossilized attachment-like footprint on the ocean floor.
That has a subtle poetic quality that is difficult to ignore. It turned out to be, in essence, the remnant of a creature that was merely attempting to cling to something solid in the dark. The actual anemone had vanished. All that was left was this tiny, enigmatic, golden trace.
However, it is worthwhile to consider the wider implications. Morphological analysis, genetic sequencing, bioinformatics knowledge, and the institutional memory of a researcher who had spent years studying the same species were all necessary for this identification. It required more than two years and a multi-institutional team. Furthermore, the deep ocean, which makes up most of the planet, is still virtually unexplored. What else is waiting to perplex someone while perched on a rock down there?
Moments like this are the reason to keep returning, as stated by NOAA‘s acting director of Ocean Exploration. The mystery of the golden orb has been solved. However, the ocean continues to surprise people.
