Mortars and pestles have been invented in the stone age, when humans found that processing food and various other materials by grinding and crushing into smaller particles allowed for improved use and various advantages, such as hard grains could be cooked and digested easier if ground first, grog would vastly improve fired clay and larger objects such as blocks of salt would be much easier to handle and use when ground and pulverized into smaller pieces. Various stone mortars and pestles have been found, while wooden or clay ones would perish much easier during the course of time.