Eating mold sounds pretty scary, but chances are you've probably done it once or twice without even realizing it. When cleaning out your fridge, you toss the obvious, clearly ancient items coated in something that's green, gray, or fuzzy, and almost always gross. But what if you reallllly want to eat the rest of that cheese? Or, worse, what if you miss it and accidentally eat mold?Mold is microscopic fungi that can grow on plants or animal materials, according to the United States Department of Agriculture Food Safety and Inspection Service (USDA). It grows in a threadlike shape with branches and roots that can grow deep into a food. Mold spores are the reproductive "seeds" of mold that can travel through the air and land on substances, and then grow into mold.