In the seasonally dry, deciduous forests of northeastern Brazil, obscured by walls of thorny-scrubs, is a vast landscape made up of tens of millions of densely packed earthen mounds. These cone-shaped piles of dirt, each measuring thirty feet wide at its base and twice as tall as a grown man, are waste earth excavated by the termites when they burrow tunnels under the soil. Researchers estimate that there are some 200 million mounds here, covering a vast region nearly equal to the size of Great Britain. The amount of soil excavated is over 10 cubic kilometers, equivalent to the volume of 4,000 great pyramids of Giza. This makes them the biggest engineering project by any animal besides humans. Incredibly, some of these mounds are as old as the Pyramids themselves.