What is "cyathaspis"

Cyathaspis is the type genus of the heterostracan order Cyathaspidiformes. Species are found in late Silurian strata in Europe, especially in Great Britain and Gotland, Sweden. The living animal would have looked superficially like a tadpole, albeit covered in bony plates composed of the tissue aspidine, which is unique to heterostracan armor.

Cyathaspis ludensis is the earliest British vertebrate fossil. It was found in rocks at Leintwardine in Herefordshire, a noted fossil locality.