| It is considered that they were used with a mill stone as a pair and were used for grinding acorns or various seeds to produce flour, or for grinding stones to get materials for pigment or earthenware. |
すり潰すための石器である磨石と対になり、ドングリなど種実類の製粉など植物加工をはじめ、顔料や土器の材質となる石の粉砕などの用途が考えられている。 |