Single-celled fungi are called yeast. Yeast is too small to be seen individually with the naked eye, but it can be seen in large clusters on fruits and leaves as a white powdery substance.
Some fungi are multicellular, such as molds and mushrooms. Molds form long strands of cells known as hyphae. They also form the fleshy part of the mushroom. The hyphae make up the mushroom in some species of molds.
Fungi do not make their own food energy; instead, they eat organic matter or the tissue of plants and animals. They create enzymes to break down the matter into smaller sizes that they can absorb.