If you fly over the south-west corner of Africa, you might see mysterious circles pockmarking the landscape. These barren patches among otherwise grassy terrain are called fairy circles. They almost seem alive, growing and shrinking with a lifespan of 30 to 60 years. Local myths say that they’re the work of supernatural entities, and scientists have tried to come up with better explanations for decades. Perhaps they’re made by grazing ants, or radioactivity, or plants that kill their competitors, or toxic gases released from the ground.

But Norbert Juergens from the University of Hamburg thinks that none of these ideas hold water… unlike the fairy circles themselves.

The circles, according to him, are water traps created by a sand