Dung beetles are beetles that feed on feces (dung). Many scarabs are scavengers that recycle dung, carrion, or decaying plant material. Some beetles found in dung and carrion are in fact predatory. Travelers gathered and ignited dried cow dung to cook their meals. The next morning he observed a young woman making cow dung patties. These they filled with driftwood, musk ox dung, and bones. The cow dung ensures that the roof is waterproof. Examples of detritivores include earthworms, woodlice and dung beetles. This legend is remembered through the ritual of building small mountain-like miniatures from cow dung. These are long cylinders made from a mixture of unbaked mud, straw, and dung. Use of dried animal dung is also possible. Dried bison dung was fuel for the fires. Cattle have a natural aversion to feeding around their own dung. Among the kinds of dung commonly used were those of dogs or pigeons. The most common material is mammal dung, usually from cattle.