Scientists discover ‘living fossil’ thought to have been extinct for 273mn years on ocean floor near Japan

Two symbiotic marine lifeforms who somehow evaded the prying eyes of human scientists and ‘disappeared’ from the fossil record over a quarter of a billion years ago have been found thriving offshore of Japan.

The creatures in question are non-skeletal corals and crinoids, or sea lilies, who were found proliferating on the floor of the Pacific Ocean, 100 meters (330 feet) below the surface, off the coasts of Honshu and Shikoku in Japan. 

They managed to survive undetected, having gone AWOL from the fossil record for longer than modern humans are thought to have existed (200,000-300,000 years ago).

“These specimens represent the first detailed records and examinations of a recent syn vivo association of a crinoid (host) and a hexacoral (epibiont),” the researchers wrote. 

Crinoids and corals shared a long, symbiotic relationship together millions of years ago, in which the corals would use the crinoids to climb higher off the seafloor to gain access to more food found in passing ocean currents.

The joint Polish-Japanese research team, led by paleontologist Mikolaj Zapalski of the University of Warsaw in Poland, used stereoscopic microscopy to conduct a 'hands-off' examination of the Paleozoic-era pals before scanning them using microtomography to gain a look at their interior structures.

They completed their non-invasive investigation using DNA barcoding to identify the exact species.

The researchers found that these newly rediscovered specimens did not modify the structure of the crinoids' skeletons, providing a possible clue as to why they disappeared from the fossil record for so long; fossils of soft-bodied organisms are vanishingly rare.

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