The Enigmatic Cambrian Fossil Volborthella and Its Occurrence in California

Volborthella Schmidt is a minute, tubular, agglutinated, and conical fossil that is composed either of oriented heavy mineral grains or quartz and other mineral grains. It is found abundantly in Lower Cambrian strata in northern Europe and is reported for the first time from western North America. The fossil has been referred to the Cephalopoda, Pteropoda, Tunicata, Protozoa, or to an unknown group of organisms. In its selectivity and orientation of the mineral grains, tubular form, and absence of shelly material, Volborthella is similar to certain agglutinated foraminifera or polychaete worm tubes but certainly not to mollusks or tunicates. Volborthella is not assigned to a particular group but is regarded as possibly a small polychaete tube or a wormlike animal of unknown affinities.