Answer:
Index fossil that is also known as indicator fossil is used to determine the age of the layers of the rocks. It says that the new layer of sedimentary rocks lie over the old layer.
The deeper we go, the older the rocks we will find. Index fossil of animals that lived or survived only for a short period of time are very useful. An example of index fossil can be Ammonites that were found in Mesozoic era that was about 25-35 million years ago.
Allegedly, <span>the finger tips show where the wind blew when our ancestors were created. In a way, their fingertips are roots to their ancestors, so touching them somehow links them to their ancestors. And as you probably know, the Navajo are very much connected to their ancestors, and tribes in general. </span>
The external ear structure is called the Pinna.
The Pinna helps to channel sound waves into the ear.
Many animals have the ability to move their pinna towards the direction of sound.
I have attached an image of a dog's ear to show you the external structure called the Pinna.
I hope this helps! I'm happy to answer any other questions you might have :)
[Image sourced from: https://www.msdvetmanual.com/dog-owners/ear-disorders-of-dogs/ear-structure-and-function-in-dogs]