Kōgoishi
Kōgoishi (神篭石 or 神籠石) are earthenwork structures, on a stone foundation, constructed in Japan during the Asuka period, particularly in areas around Fukuoka, on the island of Kyūshū. The name "kōgoishi" means "stones of divine protection," a name given them by the Meiji period archaeologist Tsuboi Shōgorō, who conjectured that they served as spiritual or practical protection for sacred sites.