The outline of the exoskeleton Orygmaspis is inverted egg-shaped, with a parabolic headshield (or cephalon) less than twice as wide as long.

The well-defined central raised area (or glabella), excluding the backward occipital ring, is ¾× as wide as long, moderately convex, truncate-tapering, with 3 pairs of shallow to obsolete lateral furrows.

The remaining parts of the cephalon, called fixed and free cheeks (or fixigenae and librigenae) are flat.

The fracture lines (or sutures) that in moulting separate the librigenae from the fixigenae are divergent just in front of the eyes, becoming parallel near the border furrow and strongly convergent at the margin.

Its axis is slightly wider than the pleural fields to each side, and has up to 4 axial rings and a terminal and almost reaches the margin.