By reducing the hydrogen and oxygen content of most of the sugar molecules by one water molecule and combining them to form large molecules, plants produce substances such as starch, inulin , and fats and store them for future use. Regardless of whether the stored food is used later by the plant or consumed by some other organism, the molecules will ultimately be digested and oxidized, and carbon dioxide and water will be discharged. Although protein substances may pass from organism to organism, eventually these too are oxidized and form carbon dioxide and water as cells wear out and are broken down, or as the organisms die. At various times in the Earth's history, some plant and animal tissues have been protected by erosion and sedimentation from the natural agents of decomposition and converted into substances such as peat, lignite, petroleum, and coal. Almost everything around us today has some connection with carbon or a carbon compound.
Carbon is in every living organism.
Without carbon life would not exist as we know it. Beggott, Jim Great Balls of Carbon New Scientist, July 6, 1991.