their shell(s), thus may have had a simpler scleritome than Halkieria and its ilk, concordant with the sclerites' simpler internal anatomy. The genera Siphogonuchites, Dabashanites, Lopochites, and Maikhanella all seem to represent components of the Siphogonuchites animal. Sclerites of Drepanochites can be distinguished based on their aspect ratio. Maikhanella is shell formed of Siphogonuchites sclerites that are fused together with a calcified matrix. Juvenile shells appear not to incorporate sclerites. The central cavity of the Siphogonuchites sclerite is simple, with no lateral chambers attached. Ninellids The ninellids, typified by Ninella, are a Lower Cambrian group that had an even simpler scleritome, with only one sclerite type (although variation in the morphology of the sclerites is observed, and left- and right-sided sclerites exist). Their sclerites are hooked or scoop-like, and are very similar to halkieriid or siphonogunuchitid sclerites; they were hollow and calcareous and had a ridged upper surface. Hippopharangites Hippopharangites has sclerites with a broad central cavity and small pores opening through the shell wall, equivalent to the lateral chambers of other halkieriids (and the aesthete canals of Chitons?) This genus is the closest in form to Chancelloriid sclerites, and is thus used to support the union of halkieriids and chancelloriids as Coeloscleritophora. Lomasulcachites Lomasulcachites is a further genus known from sclerites alone. Sachites Sachites Meshkova 1969 is a genus that comprised spiny sclerites; many Sachites specimens are now referred to other halkieriid taxa. Although believed to be related to the halkieriids, a chancelloriid affinity has more recently been proposed. Sinosachites Sinosachites is a genus of 'halkieriid' known only from sclerites; these have internal chambers that are sub-perpendicular to the central canal, to which they are connected by narrow channels. The chambers are the same diameter, ~40 µm, as the longitudinal canals in Australohalkieria; their greater number and arrangement as lateral rather than longitudinal bodies reflects the greater size of the Sinosachites sclerites, which measure about 1–2 mm in length. The sclerites are synonymous with Thambetolepis, which was originally described from Australia. Left-hand and right-hand sclerites exist, so the animal was bilaterally symmetrical; as in Halkieria, palmate, cultrate and siculate sclerite morphologies exist. Oikozetetes Oikozetetes is known only from two types of cap-shaped shell found in the Burgess Shale and dated to about . The two types are thought to be the front and rear shells of a halkieriid. They were probably calcareous while the organism was alive (although diagenesis