Water and wind can be tricksters. Over time, these erosional forces can sculpt rocks, shells and other natural materials into shapes that appear to be the work of human hands (or of those of our evolutionary ancestors). Sometimes amateurs and archaeologists alike mistake these geofacts — a mashup of geology and artifact — for stone tools, projectile points and even figurative art. Fortunately, science has tools to determine whether the object was fabricated, or just a fluke. And that’s a fact.