Bones seem solid and unchanging, but in fact your bones are constantly being destroyed and recreated—a process called remodeling—throughout your lifetime.
Inside your bones, two types of special cells are continually at work: Osteoblasts make bone, while osteoclasts destroy it. In this way, your skeleton adapts to the stresses you put on it, growing thicker here, thinner there, much like muscles growing or shrinking in response to exercise, or the lack of it.
Teeth are different. Once formed, they don’t remodel. This makes them useful for paleontologists in several ways. First, distinctive features like a tooth’s size and shape can help identify the species of its former owner, as well as details such as its age and diet. In addition, microscopic patterns preserved in the enamel can give information about the owner’s overall health during development.