Fungus: a phylum of lower plants, which has no chlorophyll, has obvious nuclei in hyphae, and propagates with sexual spores or asexual spores. The mycelium mainly absorbs ready-made nutrients from the outside to maintain life. Usually parasitic on other objects, it is widely distributed in nature, such as yeast, Penicillium producing penicillin, mushrooms and Tricholoma matsutake in food, fluffy things that have been moldy for a long time, and some pathogens.

Bacteria: a large class of microorganisms, so tiny that they must be seen with a microscope. There are many kinds, such as spherical, rod-shaped, spiral, arc, linear, etc., which are generally propagated by dividing plants. It is widely distributed in nature and plays a great role in the material cycle of nature. Some bacteria are beneficial to human beings, and some bacteria can cause diseases of human beings and livestock.