A few months later in 2006 Butterfield returned to the fray. As in 1990, he argued that "Wiwaxia"’s sclerites were internally much more like the bristles of polychaete annelids such as "Canadia" than like any forerunner of molluscan shell plates; since a 2005 paper had downplayed this argument with the comment that similar bristles also appear in molluscs and brachiopods, he pointed out that modified bristles appear as a covering over the back only in polychaetes and hence "Wiwaxia"s sclerites should indeed be regarded as like polychaetes' bristles.