A. argo, as with all other amphiaspidids, is thought to have been a benthic filter feeder that lived on top of, or buried just below the surface of the substrate of hypersaline lagoon-bottoms.

So far, A. argos is known from at least one, incomplete cephalothoracic armor that is shaped vaguely like a pillow and is, from anterior to posterior, 24 centimeters long.

[1] The armor has a pattern of lateral sensory line canals.

There is a prominent dorsal spine on the dorsoposterior end of the cephalothoracic armor.

This article related to a Devonian jawless fish is a stub.