Fungi are eukaryotic organisms. This means that their cells have a nucleus and other membrane-bound organelles, which are characteristic features of eukaryotic cells. Unlike prokaryotic cells, which lack a defined nucleus and are generally simpler in structure, eukaryotic cells are more complex and can form multicellular organisms. Fungi have a unique cellular structure that includes a cell wall made of chitin, distinct from the cellulose found in plant cell walls. Examples of fungi include mushrooms, molds, and yeast, all of which share this eukaryotic cell structure.