(However, in 1994, plant opals or cell components, from leaves, etc., of gramineous plants were found inside the fragments of earthware from the Minamimizote site located in Soja City, Okayama Prefecture, which was classified as a site from the end of the Jomon period.)
（しかし、1994年、縄文末期に属する岡山県総社市の南溝手遺跡（みなみみぞていせき）の土器片中からプラント・オパール（イネ科植物の葉などの細胞成分）が発見された。）