These fossils are very useful for us because we can use them to date the layers of rock that they are found in. Fossils that can be used in this way are called index fossils, and rock layers with the same index fossils in them can be correlated. Not my answer, link here for full
http://peter-mulroy.squarespace.com/correlating-rock-layers/
The answer is : Heat and/or pressure metamorphism
They produce narrow-band high-frequency sound to help them navigate in water. These high-frequency sounds are used in echolocation. Echolocation is used to identify and locate prey and also avoid the predators. Marine mammals like whales and dolphin use echolocation in different manners.
Answer: True
Explanation: The importance of mitotic cell division is to produce two daughter cells that are genetically identical. The genetic materials of the parent cell are arranged and moved towards the two spindle poles with the help of the spindles so that there will be an even distribution of the parent cell's genetic materials between the resulting two daughter cells.