Flexi Says: Though matter can change states, and it often does, matter cannot be created or destroyed. Similar to the law of the conservation of energy, the law of conservation of mass states that the mass (or matter) of an isolated system will remain constant over time. This means that mass or matter cannot be created or destroyed, although it may be rearranged and changed into different types of substances. Hence, matter is continuously recycled, resulting in the so called "circle of life." The carbon and other elements of organisms are recycled to be used by other living organisms.