Chlorella is a green single-celled algae cultivated in fresh water ponds. It has a grass-like smell because of the high amounts of chlorophyll in it, the highest concentration of any plant in the world. It has existed on the plant for billions of years and was one of the first foods to appear. Fossils of Chlorella have been found dating back 3 billion years. Chlorella is one of the healthiest, most potent foods in existence. In addition to being a perfect food for humans, lower grades of Chlorella are fed to livestock all over the world.