Two years ago, Barry and Aimee Brown began photographing “hidden” letters in the brain coral colonies around Curacao, the Caribbean island where they live. Their hunt, which sometimes took them as deep as 100 feet, gave them an even better understanding of the devastation shallow-growing brain coral have experienced from bleaching and recent strong storms. You can download the full set of letters for free aquí as a zip file. The photographers only ask that you give them credit and that you don’t use the work commercially.