In the process of evolution, there are many key biological differentiation, and with the geological time and evolution process, we can summarize the evolution schedule. The earliest remains of life appeared about 3.8 billion years ago, while prokaryotic single-celled organisms appeared 3.3 billion years ago. Algae and molluscs appeared 600 million years ago. Paleozoic started from the Cambrian explosion 543 million years ago to 5. 10 billion years ago. The earliest vascular plants appeared 439 million to 490 million years ago. From 363 million years ago to 290 million years ago, vascular plants began to develop into big forests, the earliest seed plants and reptiles appeared, and amphibians ruled the earth. Then the Permian happened.