Bioluminescence, the ability of living organisms to emit light through chemical reactions, has been discovered to have originated in animals at least 540 million years ago, according to a new scientific study. This finding, based on research on ancient marine invertebrates known as octocorals, significantly predates the previously established oldest known occurrence of bioluminescence by around 300 million years. The study suggests that the common ancestor of all octocorals possessed the ability to bioluminesce. Experts remain uncertain about the initial evolutionary drivers of bioluminescence, but it is known to play a crucial role in various animal behaviors, including camouflage, mating, communication, and hunting.