On a warm spring night in the coastal city of Townsville, Australia, two scientists settled into a canoe on the Ross River. Cameras in their laps and binoculars in hand, they made their way through the water.

Before long, they noticed something odd: Krefft’s river turtles basking in the moonlight, just as they do during the day.

"I didn't really think much of it at the time," says Eric Nordberg, an ecologist at the University of New England in Australia. "You very rarely these days get to discover something that nobody else has seen."

But when they asked around after that evening in 2017, they found that other scientists hadn't heard of turtles basking at night, and there were no