ostracoderm
/ˈɒstrəkəʊˌdɜːm/noun
1- an early fossil jawless fish of the Cambrian to Devonian periods, having a heavily armoured body甲胄鱼。
1.1
- Class Agnatha: several orders.无颌纲：数目。
词源
late 19th cent.: from modern Latin Ostracodermi (former taxonomic name), from Greek ostrakon 'shell' + derma 'skin'.