Figure 4From: Life cycle evolution: was the eumetazoan ancestor a holopelagic, planktotrophic gastraea?Larval and adults shells of Lower Cambrian helcionellids. A, Apex of a centimeter-large adult showing the larval shell. B, A “small shelly fossil” showing the exact same morphology as the apex of the adult helcionellid. C, Detail of the sculpture of the adult shell. D, A whole fossil helcionellid. Modified from [48].Back to article page