The fairy circles of the Namib

Bare circular patches in the grass, 2 to 12 metres across, spread in a startlingly regular pattern across arid Namibian grassland, and in 2014 found in the Pilbara in Western Australia too. This is one of the few genuinely open questions on this map. Norbert Juergens argued sand termites make them by eating out the vegetation and burrowing, so water collects and the ring of grass around the edge thrives; Walter Tschinkel’s reply was that a very strong correlation is still not causation. The competing account is self-organisation: grasses competing for scarce water spontaneously settle into a spotted pattern, the same mathematics that puts spots on animals. A 2022 study found the grass inside the circles died of water stress and not of termites eating the roots, and a 2025 review concluded self-organisation is the only theory consistent with all the field observations. Not settled, but moving.