Traditionally "fungi" include the organisms we call mushrooms, puffballs, truffles, morels, chanterelles, matsutake, lingzhi, moulds, rusts, smuts and yeasts as well as microbes living in soil, wood, water and other living things (This includes smelly feet!). However, we now know that these groups belong to very different branches of the Tree-of-Life and major changes to the classification of fungi have been proposed. Many of these "fungi" groups provide important ecosystem services. By decomposing organic matter, fungi recycle nutrients by releasing carbon, phosphorus, nitrogen, and other important elements of life back into the environment for other organisms to use. Some biologists estimate that there are 1.5 million species of fungi, although only about 98,000 have been described. They are thus one of the most diverse but least known kingdoms of life.