Once thought to be extinct, lobe-finned coelacanths are enormous fish that live deep in the ocean. Now, researchers reporting in an online article in Current Biology on June 17, 2021 have evidence that, in addition to their impressive size, coelacanths also can live for an impressively long time--perhaps nearly a century. The researchers found that their oldest specimen was 84 years old. They also report that coelacanths live life extremely slowly in other ways, reaching maturity around the age of 55 and gestating their offspring for five years. "Our most important finding is that the coelacanth's age was underestimated by a factor of five," says Kélig Mahé, PhD, of the IFREMER Channel and North Sea Fisheries Research Unit in Boulogne-Sur-Mer, France. "Our new age estimation allowed us to re-appraise the coelacanth's body growth, which happens to be one of the slowest among marine fish of similar size, as well as other life-history traits, showing that the coelacanth's life history is actually one of the slowest of all fish."