Your bones are living tissue.
Specialised cells break down old bone and build new bone throughout your life.
Bone is a living material made up of cells, proteins such as collagen, and minerals. Its structure changes over time through a process called remodelling.
Osteoclasts remove old bone. Osteoblasts lay down new tissue that hardens as minerals build up. A third type of cell, the osteocyte, helps coordinate the process.