Mike Stanford, who snapped this photo, assures that snow doughnuts are real — but rare — natural occurences.

"It's formed by a clump of snow falling off of a cliff or a tree into the snow pack. And if the conditions and temperature are just right, as gravity takes over, it pulls the snow down, and it rolls back on itself," Stanford says. "Usually the center collapses and it creates what we call a pinwheel."

Via here