Drepanaspis

Drepanaspis gemuendenensis is an extinct species of primitive jawless fish from the Devonian Hunsrück lagerstätte.

Description
It was a flattened creature with a heavily armored body, somewhat ray-like in appearance. Its mouth faced upwards, unlike most other Heterostracans, which had downward-facing mouths. Drepanaspis also had small, widely spaced eyes. It is presumed to have foraged the ocean floor for food.[1]

This frying-pan shaped fish may have been the ancestor of the giant, meter-long, meter-wide Psammosteid heterostracans of the late Devonian.