In addition to storage chambers, the centre of the tunnel system includes a nest, and a separate latrine chamber. The tunnels are entirely closed off from the surface, although their presence may be evident from dome-shaped mounds of excavated material similar to mole hills. As a result, there is little circulation of air within the tunnels, which are therefore hypoxic and humid, but are protected from extremes of weather. The mole rats occasionally travel above ground to forage for surface vegetation, and to disperse to found new burrow systems.