Fossils of the various species are found in Middle Cambrian-aged marine strata of Eurasia and North America, about 513 ± 0.3 to 499 ± 1.7 million years ago.

The central raised axis, that is defined by a furrow, is moderately convex and narrow, at its widest about ⅛ of the maximum width of the headshield (or cephalon).

The part of the axis in the cephalon, called glabella, tapers forward, is rounded-truncate at its front, is inserted by for pairs of furrows that do not contact across the midline, and one at the back that defines the occipital ring.

Between the front of the glabella and the border, is a somewhat convex area of the cheek that is comparable in length (along the midline) to the occipital ring.

In well preserved specimens the cheeks in front of the eye are adorned with very fine ridges (or striae) that probably represent parts of the digestive system (see Kordule, 2006, p. 283, figure 2.a/f).