Many other researchers, including entomologists and botanists, aren’t convinced. They think the circles occur because plants engage in a tug-of-war for water and other scarce nutrients. Due to their battles, the landscape “self-organizes” into rings of deep-rooted grasses, draining water from a central reservoir where no other plants can thrive. This explains why, as the researchers Michael Cramer and Nichole Barger found in 2013, the fairy circles are restricted to places with low rainfall, and why they grow after dry years and shrink after wet ones.

Namibian fairy circles (Stephan Getzin)

Stephan Getzin from the University of Goettingen started off as a fan of the termite hypothesis when he began studying the fairy circles in 1999. But he defected to the self-organization camp after studying aerial images of the fairy circles, and seeing just how regular they are. “They have an extremely regular hexagonal spacing, like a honeycomb,” he says. “That pattern persists throughout the landscape for hundreds of thousands of meters. Termites and ants are not known to cause such strictly ordered patterns.” In May 2014, he published a paper outlining his evidence for the self-organization hypothesis.

Three days later, he got an email from Bronwyn Bell, an environmental manager at an iron-ore mine in Newman. We have something similar here, she said. To prove her point, she attached an aerial photo. “When I saw it, it looked really convincing,” says Getzin. Seven months later, he was on a plane bound for Newman.

Getzin and his colleagues found that the Australian circles exist in the same orderly honeycomb as their Namibian counterparts, with almost exactly the same spatial traits. And by measuring temperature and analyzing soil samples, they worked out how the circles might form.

The critical point is that the area around Newman doesn’t get enough rain to sustain an even carpet of plants, so there’s competition for water. Plants that grow a little bit bigger than their neighbors draw in more water: Their deeper roots loosen the soil around them, allowing more water to seep in. Nearby plants benefit, while those further away die of drought. They leave patches of bare earth that are too hard, compact, and hot for seeds to germinate. These empty circles act as rain collectors: any water that falls on them runs off to the side, where it nourishes the encircling plants.

When Getzin simulated all of this on a computer, he produced virtual patterns that are almost indistinguishable from the actual fairy circles.

He thinks that the Namibian circles form in a slightly different way. There, the fight for water mostly occurs underground; in Australia, it happens on the surface. But the basic idea is the same: Water conflicts that play out over meters create patterns that pockmark the land for kilometers. “The new paper moves us closer toward a unifying theory of fairy-circle formation,” says Barger.