A 'Golden Orb' on the Ocean Floor Came From a Mysterious Animal

This species can reach 30 centimeters in diameter and live between 1,600 and 4,000 meters deep. Its biology baffles specialists because it does not quite fit the rules that define anemones and corals. Since its discovery, scientists have struggled to classify it, and its evolutionary origin remains uncertain.

Relicanthus daphneae moves across the ocean floor.

‘National Oceanic and Atmospheric Administration (NOAA) | Office of Exploration and Research (OER)’

Before the study, there was nothing linking the golden orb to the giant anemone. The report details that an initial examination found spirocytes—ultra-specialized cells that only cnidarians (the group of animals made up of anemones, corals, and jellyfish) have. This finding ruled out the possibility that it was an egg or a biofilm, as initially thought.

The team then sequenced the DNA of the material to search for matches in databases. The complete mitochondrial genomes showed a 99.9 percent match to Relicanthus daphneae. The evidence pointed to the orb being part of a rare and poorly documented anemone. However, the remains did not match any known structures of this species or other anemones.

Close up of a cuticle detached from the anemone.

NOAA Ocean Exploration

To solve the riddle, the researchers revisited a specimen collected years earlier and studied it again. They found fragments of a multi-laminated, golden cuticle the anemone had produced around its base. They then looked at live specimens and discovered that, as it moves along the bottom, R. daphneae leaves behind this cuticle, which remains on the rocks until it disintegrates or is buried.