One of the most severe glaciation event known in the geologic record occurred during the Cryogenian period of the Neoproterozoic, when global ice sheets may have reached the equator and created a "Snowball Earth" lasting about 100 million years.

Possibly as a consequence of the low-latitude position of most continents, several large-scale glacial events occurred during the Neoproterozoic Era including the Sturtian and Marinoan glaciations of the Cryogenian Period.

Nineteenth-century paleontologists set the start of multicellular life at the first appearance of hard-shelled arthropods called trilobites and archeocyathid sponges at the beginning of the Cambrian Period.

At least 25 regions worldwide have yielded metazoan fossils older than the classical Precambrian–Cambrian boundary (which is currently dated at 538.8 million years ago).

The Doushantuo Formation (of Ediacaran age) preserves fossils of microscopic marine organisms in great detail.

[7][contradictory] The Huainan biota (of late Tonian age) consists of small worm-shaped organisms.

Possible keratose sponge fossils have been reported in reefs dated to c. 890 million years before the present, but remain unconfirmed.