claim: David Attenborough was controller of BBC Two.
evidence: The Coelosclerithophorans are a polyphyletic group of organisms bearing hollow sclerites made of aragonite , and with an allegedly distinctive microstructure .. polyphyletic. polyphyletic. sclerites. sclerites. aragonite. aragonite. Their skeletons may be homologous to those of the molluscs , and Halkieria looks very much like a polyplacophoran .. Halkieria. Halkieria. polyplacophoran. polyplacophoran. The shells of this group and the molluscs appear to have originated in the same fashion .. However , there are several reasons to doubt this relationship , many of which may not pass muster .. There are two groups within the coeloscleritophorans  : the Sachitids , to which Halkieria and Wiwaxia belong , and the Chancellorids .. Chancellorids. Chancellorids. Halkieria. Halkieria. Wiwaxia. Wiwaxia. The Ediacaran fossil Ausia has been touted as an ancestral ` intermediate ' between both of these groups .. Ausia. Ausia fenestrata. These are common constituents of Lower Cambrian small shelly fossil assemblages .. Cambrian. Cambrian. small shelly fossil. small shelly fossil