Animal corpse decomposing on the forest floor, covered in decay and fungi. Microscope image of fungi. Hand of scientist culturing staphylococcus in a petri dish. Hand takes a sample of penicllium notatum from a piece of moldy cheese and places that in a petri dish. Scientist places penicillium in a agar dish and holds it up to light to show how penicillium has stopped bacteria from growing. This is how penicillin works. Leafy forest floor. Close ups of mold. Penicillium being irradiated with ultraviolet light to create medical grade penicillin.