The Namibian savanna is dotted with 13-foot-tall towers of sandy soil. Built by termites just a fifth of an inch long, these mounds aren’t only structural feats—they’re a biological extension of the 1.5-million-bug colony inside. Though researchers are still trying to figure out how the “brain” of the swarm works (how do termites plan a mound without any blueprints?), they’ve recently uncovered a lot about the entomological monuments. “The functioning organism is really the whole colony,” explains Hunter King, a physicist at the University of Akron who studies the mechanics of insect swarms. “The mound really is the lung and the respiratory exchanger—and a protective skin for the superorganism.” Here’s how these skyscrapers work.