Although life forms in the Fungus Kingdom (molds, mushrooms, and yeasts) may seem like plants, they are actually more closely related to animals. In the history of life, fungi and primitive animals branched apart after plants had evolved.|
Like some kinds of animal cells, the cells of fungi are surrounded by walls made out of chitin, a complex molecule made of sugar and nitrogen. Plants use cellulose for their cell walls.
Fungi get their energy by breaking down organic molecules which they soak up directly from their environment. They emit substances that chop complex organic molecules into smaller ones that are easy to absorb. Fungi are vital to the global ecosystem because they are so good at breaking down anything organic.