Sedimentary rocks are 'built up' over time, and if something dies overtime, lets say an animal, it will get buried and minerals will fill it and it becomes a fossil. fossils are important because they tell us about the past and what is was like way back when.
Each pH is 10 times stronger than the other. Ph5 is 10x stronger, ph6 is 100x stronger, and so on. Ph8 is a 10000x stronger base than a solution with a pH of 4
The main significance of an eyespot in the cell of euglena is the detection or sensing of light and then orienting the organism away from or towards the light. Euglena is basically a genus of a single celled flagellate. I hope that this is the answer you were looking for and it has come to your help.