Ammonite Fossils in Limestone Blocks Used for the Castle Walls
Many castle walls in Okinawa have been built from Ryukyu Limestone which was formed from coral from tens or hundreds of thousands of years ago. However, the walls of Nakijin-jo Site use ancient limestones from the geological stratum of the surrounding area (the Nakijin stratum), which dates from the Mesozoic era, approximately 230 million years ago.
This limestone contains ammonite fossils, which lived in the oceans from between approximately 65 million to 400 million years ago. The ammonite is a relative of the squid and the octopus, and is related to the present-day nautilus. Forty-four different species of ammonite fossil have been discovered in the stratum around Nakijin Village, and are a valuable source of information in understanding the history of the Ryukyu Archipelago.
许多的冲绳数万的墙壁-内置的石灰石从珊瑚礁数量 100000 年前，但现在周围的地层中今归仁城堡城墙现在今归仁形成） 包含大约 2 亿 3000 万多年前的旧石灰石，可以从中生代捉住。
亚扪人此石灰石所载化石曾生活在海洋中约 4 亿 ~ 6500 万多年前从现在开始。亚扪人、 乌贼和章鱼的同伴，到当前的鹦鹉螺号是关闭。今归仁村地区的地层从现在已成为有价值的文章，已发现的亚扪人化石是 44 类型，知道琉球群岛的历史。