And these cells are capable of taking up calcium as well as phosphate from the blood and depositing it into the extracellular matrix. So basically, these are the cells that are responsible for building bones. They secrete organic as well as inorganic matter such as collagen, calcium as well as phosphates, and are responsible for creating the extracellular matrix that we just discussed above. Now, eventually, when these cells completely surround themselves and enclose themselves with the matrix, they basically become, they differentiate into a second type of cell known as an osteocide. Now, what exactly is an osteocide? Well, basically, the osteocide is the most common type of cells found in the bone.