Any member of the eukaryotic group of creatures, which also includes mushrooms and microbes like yeasts and molds, is referred to as a fungus (fungi).
The majority of fungi are decomposers that obtain nutrients from dead or decomposing organic materials (usually plants).
Fungi have a rigid cell wall composed of complex polysaccharides such as chitin, glucans, and glycoproteins.
In some adult organisms, the cell wall provides structural structure, rigidity, and protection from aridity and prey, which means it can be extremely tough.