All forms of mold are a type of fungus. Mold draws all of its nutrients directly from other plants, animals and food. Bread mold typically appears as a green or black fuzz growing on the surface.
Mold spores range from three to 40 microns in size. Mold that is visible to the naked eye is actually a single organism that has grown from a spore. Bread is susceptible to mold because it retains moisture and is typically stored at room temperature. Refrigeration can slow but not completely stop mold formation. Moldy food should be discarded. Ingesting it can cause nausea, vomiting and possible respiratory problems if inhaled.