Bread mould is a saprophytic fungus. Saprophytes obtain their nutrition from dead and decaying organic matter. They secrete digestive enzymes onto the food material outside their bodies. These enzymes break down the complex food molecules into simpler, soluble substances that the mould can then absorb through its hyphae. Cuscuta is a parasitic plant, lice are parasitic insects, and tapeworms are parasitic flatworms; all of these obtain nutrition from living organisms, not through external digestion.