Heterosteus

A giant of the ancient seas
With flattened body and tiny eyes
A placoderm with armoured plates
And bony jaws with no teeth

He lived in the Middle Devonian
In Europe, Greenland and Spitsbergen
He might have fed on tiny prey
With his weak jaws and small gaze

He was related to Dunkleosteus
But had his eyes on stalks protrude
He was the largest of his kind
Heterosteus, a fish sublime