Marine biologists studied the growth of urchin larvae at a coral nursery in Key Largo as part of an initiative to regrow the corals and sea urchins lost to coral bleaching.This footage captured in January by Daniel Eidsmoe shows marine biologist Jim Brittsan studying urchin larvae at a coral nursery near the Carysfort Reef Lighthouse in Key Largo, Florida. The larvae can be seen suspended on strings tethered to the ocean floor.According to the Florida Fish and Wildlife Conservation Commission, corals have a symbiotic relationship with algae. Urchins eat invasive algae that grow on coral reefs, allowing the coral to grow.Brittsan said that he feeds the larvae coral rubble to diversify their algae diets and teach them how to hide in the nooks of coral, according to Florida Currents. He describes the urchins as “underwater gardeners.”The Florida Reef experienced mass coral bleaching in the summer of 2023 during an El Nino weather pattern, leading to significant population declines in various coral species. The Keys have lost 80 percent of their coral in the past 30 years, according to Florida Currents. Credit: Daniel Eidsmoe via Storyful