National Geographic Emerging Explorer David Gruber, a marine biologist from the City University of New York, spotted the turtle by chance while filming more common biofluorescent critters in Solomon Islands.
Gruber let the turtle — a critically endangered hawksbill — go on its way, so it's not as if the glowing has been closely studied. "It'd be fairly difficult to study this turtle because there are so few left and they're so protected," he told National Geographic.
Based on his brief observation, however, Gruber suspects that the red color seen on the turtle may come from biofluorescing algae stuck to its shell — but that the green is all turtle.
Since the hawksbill was found in an area full of glowing sharks and coral, it's possible that the biofluorescence is a camouflage adaptation. But with just one brief look at this very special reptile, it's impossible to know how common the adaptation is, how the turtle manages it, or what its purpose is.