Fungus is a large group of eukaryotic organisms. Fungus types vary from mold, the familiar mushroom, and yeast. Instead of the cell walls containing cellulose, their cell walls contain chitin. Fungi can thrive on dead organisms, moist soils, or on other fungus. They are cruicial to decomposition in the world. Fungi can be used to aid in the making of bread and in the fermentation of wines and beer. Antibiotics are also another product of this kingdom. Fungi can reside in extreme climates, like deserts or areas with high salt concentration. There are over 100,000 types of fungi, and they are classified by their shape and size. Fungus reproduces asexually through their spores or by fragmentation. They can also reproduce sexually by combining hyphae through mitosis. Typically, fungi isn't harmful although some species may be pathogens to animals and other plants. Most pathogenic fungi attack trees, and are only harmful to animals if digested.