Ultraviolet light illuminates the growth rings in a cross-section of a 44-year-old deep-sea coral (Primnoa resedaeformis) collected off the coast of Newfoundland at about 1,300 feet (400 meters). Similar to tree trunks, cross-sections reveal coral-growth rings that can be used to determine their age—and information about climate. Because coral growth depends on temperature, sunlight, and nutrients, scientists can derive information about them from coral growth rate.