[throwawayzRUU6f]

A relatively recent discovery points to macroscopic multicellular life as early as 2.1B years ago (1), right after the Great Oxidization Event. We only have fossils of a single specie. Given the complexity of the specimens, it's unlikely to have been the only specie in existence. The rest of the biota is probably lost to time.

The fossil record for Ediacarian biota (pre-Cambrian age) is also very sparse. It's only after the evolution of endo/exoskeletons that we start to get proper fossil records

(1) - https://en.wikipedia.org/wiki/Francevillian_biota