The oldest fossil to be found on Earth i petrified algae.  The algae from which this petrified algae was formed once flourished in the warm seas over what is now Minnesota.  Algae is Earth's earliest plant life and has been estimated by geologists to have first lived about 2 billion 300 million years ago.  The algae from whick this fossil is made was petrified or replaced by t he mineral jasper.  The swirling pattern in the stone is where the algae use to be.