A linear, unsaturated hydrocarbon carotenoid, the major red pigment in fruits such as tomatoes, pink grapefruit, apricots, red oranges, watermelon, rosehips, and guava. As a class, carotenoids are pigment compounds found in photosynthetic organisms (plants, algae, and some types of fungus), and are chemically characterized by a large polyene chain containing 35-40 carbon atoms; some carotenoid polyene chains are terminated by two 6-carbon rings. In animals, carotenoids such as lycopene may possess antioxidant properties which may retard ageing and many degenerative diseases. As an essential nutrient, lycopene is required in the animal diet.