And if we need our calcium, this is how our bone basically releases the calcium so that the muscles can actually contract. And when we discuss the process of reforming and remodeling our bone, the osteoclast and the osteoblast basically play a crucial role in that process. So the bone is a living tissue, it's continually being reformed. So that means it's continually being broken down and reformed. And that's exactly why these two cells are crucial. Now, what about the structure of the bone?