This is called the Cambrian explosion (explosion of life, that is). All sorts of weird and wonderful creatures appeared at this time. People have found beautiful fossils of these creatures in rocks in British Columbia, Canada and, more recently, in other parts of the world. These creatures were the ancestors of all animals, including you and me. Before the Cambrian time period, life had not changed much over billions of years and very nearly died out altogether when the whole planet froze solid about 700 million years ago.