Bones were calcified, hard tissues that made up the internal skeletons of certain animals, who were referred to as vertebrates. Bones functioned to move, support, and protect the various organs of the body, such as how the skull protected a being's brain, along with producing red and white blood cells and store minerals. Bone tissue was a type of dense connective tissue. Other organics had an exoskeleton or a cartilaginous skeletal structure. After death, a vertebrate's body would decay, releasing its energy back into its ecosystem and leaving the bones behind. Over time, however, they would dissolve too ans transfer energy and minerals back into the ecosystem.