 They went on to classify the halkieriids as nearly modern molluscs, since in their opinion halkieriids' "chain mail" coats of mineralized sclerites were an advance on the unmineralized sclerites of "Wiwaxia" and also resembled the armor of some living shell-less aplacophoran molluscs, the Neomeniomorpha.As a result, they concluded that the whole "Kimberella"-"Odontogriphus"-"Wiwaxia"-mollusc lineage must have diverged from that of the annelid worms some time before the appearance of "Kimberella" in the Ediacaran period.This brought "Odontogriphus" into the center of a debate that had been going on since 1990, when Butterfield denied that "Wiwaxia" was a forerunner of molluscs and argued that it was an evolutionary "aunt" of annelids.