They call them footprints of the gods.

Whether in the thickly tufted prairie grass of the southern plains or in the dry stalks of vegetation in the dusty foothills, something is happening in Southern Africa. It doesn’t really matter what the climate or soil conditions are, or who is there to see it or not, or what grazing pattern the local wildlife happens to follow. Rings are forming in the ground.

Perfectly round, almost too-good-to-be-true rings, in fact. But they are true, and they are naturally occurring, so far as anyone can tell. The small, circular patches of bare ground form like bald spots in the otherwise thick grass or fields in Namibia and South Africa, where humans often don’t set foot. Their mysterious origin has lead them to be called “Fairy Circles” colloquially, and legends ranging from local tales of god’s footprints to international recognition as a “UFO hot spot” have sprouted up in short order.

But the Fairy Circles are not grand designs like their distant paranormal cousins, crop circles, and bona fide scientific research has led to the conclusion that not only do they occur naturally, but they grow and shrink over time, as if they were alive. Examination of the soil in and around the circles reveals no abnormal insects or parasites, no unusual fungus to speak of. All science has discovered thus far is that they’re not a hoax.

Popular hypotheses about their cause include mold or spores that kill off the grass, the radiating pattern of growth of which would certainly explain the odd circular shape; or wind or soil erosion, which would do less to explain the patterns but has been observed elsewhere and found to cause “bald spots.”

For now, the odd formations are both intriguing and entertaining to nearby residents as well as botanists and UFO enthusiasts the world over. For all the predictable supernatural talk about the Fairy Circles occupying, representing or otherwise creating a path to another world, they do in fact occupy a strange and unreal dimension—that rare place and time after which a phenomenon has been discovered, but before it is blandly explained away like so many lights in the sky. For now, the only certainty is the mystery.