Fossils in the Pre-Cambrian Rocks

   Some of the first animals found in the oldest rocks date from well over 2,600 million years ago. In these pre-Cambrian rocks nodules and layers of a limey substance have been discovered. These could have been formed by tiny water plants, called blue-green algae, in the same way that they do today. The same material is made by one-celled sea animals, called Foraminifera, which form limey shells. One scientist even gave a name to one of these first animals, dis­covered in some ancient Canadian rocks. He called it Eozoon canadense— 'the dawn-animal of Canadá'. Apart from these puzzling discoveries, pre-Cambrian rocks have also revealed traces of what might have been sponges, anemones and other worm-like creatures, but nobody is really certain what they are.