fungi are eukaryotes which may have one cell, like yeasts, or many cells, like mushrooms. they are saprophytes. fungi break down living or dead material, so they are decomposers. only fungi, and a few bacteria, can break down lignin and cellulose, two parts of wood. some fungi are mycorrhiza. they live under ground and give nutrients to plants, like nitrogen and phosphorus. eukaryotes that are not plants, animals, or fungi are called protists. most protists live in water.