Although life forms in theFungus 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 animalsbranched apartafter 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 usecellulosefor their cell walls.

Fungi get their energy bybreaking down organic moleculeswhich 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 tothe global ecosystembecause they are so good at breaking down anything organic.