四射珊瑚是一类已绝灭的古生代珊瑚,其地质历程是从4.8亿年前的中奥陶世一直延续到2.5亿年前的二叠纪末。这类珊瑚的外壁上常常长有纵脊和横向生长纹,因此,1850年英 The coral is a group of extinct Paleozoic corals, the geological history of which extends from the Middle Ordovician 480 million years ago to the end of the Permian 250 million years ago. Longitudinal ridges and transverse growth patterns are often found on the outer walls of these coral species, so in 1850 the British