Vendian

The Vendian period, also known as the late Neoproterozoic era, occurred roughly 635 to 541 million years ago. It was a time of significant Earth changes, including the buildup of oxygen in the atmosphere and the appearance of simple multicellular life. This period saw major environmental shifts, such as extensive glaciations ("Snowball Earth") and the start of more complex ecosystems. The Vendian marks a transitional phase leading to the explosion of diverse multicellular organisms in the Cambrian period, shaping the foundation for modern life forms.