What looks like ordinary sand, rocks or snow flowing in one direction can actually hide swirling currents that move in ...

But why does sand get so hot, sometimes to the point of becoming almost unbearable to walk on barefoot? The answer lies both in the nature of sand itself and how it interacts with sunlight.

How do traps work? Pit-building larvae dig traps by burrowing backward in a circle and flicking sand to the side, Brown said. They spiral downward until the sides form a steep, funnel-shaped pit.