A hawksbill sea turtle was recently found that is stumping scientists.
The turtle was glowing, but not through bioluminescence like a firefly or plankton that turns tides blue.
It's biofluorescent, according to marine biologist David Gruber.
The way it works is, rather than producing its own light, the turtle's shell reflects blue light as red and green.
Researchers have recently discovered biofluorescence in some fish and crustaceans but never a reptile like the hawksbill.
While biofluorsecence is used in some animals to attract prey, hawksbills largely feed on sponges and algae, so a more likely hypothesis — as another marine biologist told National Geographic — is camouflage.
Still, it'll take more research to understand — something that might not be possible with the hawksbill, which is critically endangered.
See more of the stunning species:
Hawksbill sea turtles
This turtle is fluorescent, and scientists aren't sure why
A Hawksbill sea turtle is seen swimming on January 15, 2012 in Lady Elliot Island, Australia. Lady Elliot Island is one of the three island resorts in the Great Barrier Reef Marine Park (GBRMPA) with the highest designated classification of Marine National Park Zone by GBRMPA. The island of approximately 40 hectares lies 46 nautical miles north-east of the Queensland town of Bundaberg and is the southern-most coral cay of the Great Barrier Reef. (Photo by Mark Kolbe/Getty Images)
Hawksbill Turtle, Eretmochelys imbricata, Namena Marine Reserve, Fiji (Photo by Reinhard Dirscherl/ullstein bild via Getty Images)
In this photograph taken on April 20, 2010, four month old Hawksbill turtles swim into the sea after a symbolic release by conservationists at the Thousand Islands National Marine Park in Pramuka island north of Jakarta. Hawksbill turtles, known by their scientific name Eretmochelys Imbricata, are listed as an endangered species by the International Union for the Conservation of Nature and Natural Resources. Hunted for their flesh, shell and eggs, plus destructive fishing methods have threatened the survival of the sea turtle. Indonesia's conservation efforts include aiming to stop the illegal trade of Hawksbill turtle products and protect its natural nesting grounds. AFP PHOTO / ROMEO GACAD (Photo credit should read ROMEO GACAD/AFP/Getty Images)
Hawksbill Turtle - Eretmochelys imbricata floats under water. Maldives Indian Ocean coral reef. (Photo via Getty Images)
Hawksbill Turtle and Diver -- Maldives. (Photo by Ian Cartwright via Getty Images)
(Photo by Stuart Westmorland via Getty Images)
Hawksbill sea turtle (Eretmochelys imbricata) swimming over coral in Jackson Reef, Tiran strait, Red Sea. (Photo by Joao Pedro Silva via Gety Images)
Hawksbill turtles have a narrow snouted hawk-like head. They are critically endangered. (Photo by Manoj Shah via Getty Images)