For years, we knew very little about the microcosmos. Bacteria and protoctists, abundant for over 2000 million years, remained soft-bodied. The great discoveries of Cambrian fossils suggest an explosion of life from virtually nowhere.
A tremendous burst of animal evolution springs from protoctist and animal biomineralization. Life rapidly radiates. All of today’s animal phyla (great groups) originate in the Cambrian Period. Magnificent fossil traces (furrows and burrows) record our own distinguished, flexible ancestors — the worms.