Ankhegs burrow with their legs and mandibles, moving with unsettling speed through loose soil, sand, gravel, and the like-they cannot burrow through solid stone. Burrowing ankhegs can construct tunnels by pausing frequently to shore up the walls with a thicker, less caustic secretion from their mouths. If an ankheg chooses to make a permanent tunnel when burrowing, it moves at half speed. A typical ankheg tunnel is 10 feet tall and wide, roughly circular in cross-section, and from 60 to 150 feet long ([1d10 + 5] × 10). Clusters of ankhegs often share the same territory and create intricate winding networks of tunnels under farmlands, sometimes resulting in sinkholes where too many burrow at once.