What were the first living organisms on Earth? In this episode, we travel billions of years backwards in time to learn how Earth was created. We hear about the significance of the nebular hypothesis theory and how Earth has changed since its inception.  We learn about the formation of our solar system, development of Earth's land, oceans and atmosphere, and tectonic plate movements. The earliest life forms on Earth were likely living unicellular organisms - autotrophs that used photosynthesis, prokaryotes (bacteria are one example), and stromatolites (colonies of unicellular bacteria). Next was the development of multi-cellular organisms - eukaryotes (paramecium cells and cells containing both organelles and a nucleus) including animal, plant and fungus cells, and specialized cells. Fossils show ancient multicellular life forms. Today more than 10 million living species exist on our planet.