This is an osteocyte, a type of cell which is found inside hard bone and co-ordinates the building and break-down of bone tissue. Its many processes (green) allow it to communicate with other bone cells and the blood supply. Understanding the structure of osteocytes may help us to understand bone diseases such as osteoporosis. This image was created by scanning the surface of a block with an electron microscope, removing a thin slice with a diamond knife, scanning again and repeating. The 3D cell was then reconstructed from the 2D slices. Scale bar = 5 µm