Its shell is very similar to one of the two Burgess Shale shell types labelled Oikozetetes; the forward shell of halkieriids, most fossils of which are dated to the Early Cambrian; and those of other Early Cambrian fossils such as Ocruranus and Eohalobia. These similarities suggest that Orthrozanclus was an intermediate form between Wiwaxia and the Halkieriids and that all three of these taxa formed a clade,[12] in other words a group that consists of a common ancestor and all of its descendants. So Orthrozanclus was also drawn into the complex debate about whether Wiwaxia is more closely related to molluscs or to polychaete worms.[2]