Stages that living things go through as they develop are called life

Stages that living things go through as they develop are usually called life periods or life epochs, depending on the author you wold read. But the basic idea behind is that there are a few different life periods through which most people go through - childhood adolesence, adulthood, and late adulthood. Each of them has their own characteristic.

The one that most represents the earths mantle would be the skin since the mantle is the upper part of the earths depths which is just like the skin of an apple.