Consumption of soil, powdered rock, termite-mound-earth, clay and mud is a common feeding behaviour in many animals. Also called “Geophagy”, several herbivorous, omnivorous mammals, birds, reptiles and insects are known to indulge in it. It appears to be more common in herbivores, especially in the tropics. Animals and birds seem to take to soil eating when their dietary toxin load is high. In some instances, it is believed that soil eating is for getting the sodium missing in plant diet. The mechanical and pharmaceutical properties of natural kaolinite-based clays are possibly countering the effects of parasites. Clay is known to be a powerful adsorbent and soils rich in clay are specifically consumed possibly to adsorb bacterial or plant secondary compound toxins. Clay is known to absorb intestinal fluids in diarrhoea. Animals are seeking to get relief from gastrointestinal distress caused by infectious parasites.

Chimpanzees, monkeys, tigers, elephants, parrots, deer are a few animals observed to mine for clay-rich, volcanic and other soils for apparently different reasons.