This sekkaku (the stone core) is accompanied by the Toryumon (bean applique design) earthenware, the Ryusenmon (linear relief) earthenware, the Tsumegatamon (finger-nail like impressions) earthenware, and so on, which are from the Incipient Jomon period.
この石核には、縄文時代の草創期の土器である豆粒文（とうりゅうもん）土器、隆線文（りゅうせんもん）土器、爪形文（つめがたもん）土器などを伴う。