Why Mushrooms Increase Longevity A recently published literature review found that eating 18 grams of any type of mushroom contributes to reducing your potential risk of cancer. Mushrooms aren’t plants or animals. They are umbrella-shaped fruiting bodies of a fungus that typically grows above ground. Mushrooms produce millions of microscopic spores that are spread by animals or the wind. Once these have germinated in wood or soil, they send out a network of rooting threads called mycelium that can persist for many years. Mycelium digests the surrounding nutrients externally and then absorbs those nutrients. Scientists don’t believe that all mushroom species have been identified. Neither do they agree on how many species there may be, with estimates ranging from a low of 45,000 cataloged species in 2015 to a high of 1.5 million to 5.1 million yet to be discovered and named. According to a paper in the American Society for Microbiology, in 2017, there were 120,000 identified species, which the researchers estimated may be just 3 percent to 8 percent of the actual total.