出典:Wikipedia
出典:『Wikipedia』 (2010/10/31 10:53 UTC 版)
The Edrioasteroids are an extinct class of echinoderm that lived from the Ediacaran (if Arkarua was indeed an edrioaster) to the Permian periods of geologic time, about 300 million years ago. The animals usually consisted of a disk-like upper body made of many plates.