Here’s the answer:
Schwann Cells
Answer:
Sedimentary rocks
Explanation: Where are fossils found? Fossils are found almost exclusively in sedimentary rocks—rocks that form when sand, silt, mud, and organic material settle out of water or air to form layers that are then compacted into rock. So the answer will be <em>Sedimentary</em> rocks.
Cyanobacteria or simply known as blue-green algae may have formed the oxygen into the early atmosphere. This is because these micro-organism has the capability to photosynthesize wherein they can produce oxygen and carbohydrates. In fact, all the plants contribute in the fomation of oxygen.
Natural springs hope this helps :D
