The Precambrian time, which spans from the formation of the Earth about 4.6 billion years ago until approximately 540 million years ago, was dominated by simple life forms. The earliest organisms were primarily prokaryotic, meaning they lacked a nucleus and were unicellular. Bacteria and archaea were the most prevalent groups during this era.
As time progressed through the Precambrian, particularly in the later stages, we see the emergence of more complex life forms. Multicellular organisms began to appear, with the Ediacaran Biota being one of the most notable groups. These were soft-bodied organisms that lived in shallow marine environments and included a variety of forms, some resembling modern jellyfish and worms.
Overall, the organisms of the Precambrian were primarily aquatic, flourishing in the oceans that covered the Earth. It wasn’t until the Cambrian explosion, which marked the end of the Precambrian, that more complex life forms, including hard-shelled organisms and more diverse ecological interactions, began to emerge in significant numbers.