Man, if I had a time machine and could go back to the billions of years when it was all soft bodied single and multi celled single critters. To see what things were like. It is completely possible there were completely different cell structures that died out and aren’t around anymore.
IIRC the first evidence we have for life is the Stromatolites left behind by cyanobacteria. I still need to hunt down a sample of them. IIRC the oldest are in Australia.
