Tel Aviv University researchers have shown that the reason why some undersea corals glow is to attract prey. Plankton, the food of predatory mesophotic (fluorescent) corals, was significantly more attracted to a fluorescent target than a clear “control” target.

https://www.aftau.org/news_item/tau-researchers-discover-why-corals-glow-even-in-the-depths-of-the-sea/

https://www.i24news.tv/en/news/israel/environment/1658068884-corals-glow-to-attract-prey-new-study-reveals