Animal embryo-like fossils from the Ediacaran Doushantuo Formation, South China, have been interpreted as the earliest metazoan fossils, significantly predating the radiation of biomineralizing animals and macroscopic bilaterians during the Ediacaran–Cambrian transition.

This article discusses the fossilization process of these controversial structures

via The origin of intracellular structures in Ediacaran metazoan embryos.