From 40 to 75% of all species on Earth are indigenous to the rainforests.[1] It has been estimated that many millions of species of plants, insects, and microorganisms are still undiscovered. Tropical rainforests have been called the "jewels of the Earth", and the "world's largest pharmacy", because of the large number of natural medicines discovered there.[2] Rainforests are also responsible for 28% of the worlds oxygen turn over, often misunderstood as oxygen production,[3] processing it through photosynthesis from carbon dioxide and through breathing to carbon dioxide.