Mystery spots: In southwestern Africa's Namib Desert, the lack of rainfall keeps vegetation sparse. Yet in some areas, mysterious rings of grass with bare centers appear and thrive. Now scientists have discovered these so-called fairy circles are indeed created by wee little creatures—termites.

Many organisms live in and around fairy circles, which range from one to 50 meters in diameter and persist for decades. But scientists writing in March in Science found only one species consistently inhabiting even the youngest fairy circles—the sand termite Psammotermes allocerus—making it the most likely culprit.

How do termites make fairy circles? When termites cluster together, feeding on and destroying vegetation, they leave a roughly circular bare patch that retains more water than the surrounding soil. The fairy circle thus acts as a water reservoir for the sand termites, the grasses around the edge and other thirsty organisms.