Figure 10b. Cambrian Hyolithid Fossil

A hyolithid fossil (Haplophrentis sp.) from the Cambrian Conasauga Formation, about 0.4 inches (10 millimeters) long. Hyolithids do not have any living relatives, so scientists are unclear about what sort of animals they are, but they believe they may belong to the Lophophorata, a group that also includes brachiopods.

Photo courtesy of David R. Schwimmer Ⓒ 2017