Every living thing on Earth depends on the presence of our little microscopic friends. Bacteria, fungi, and other microorganisms serve as the primary food source for other tiny organisms, like paramecia, worms, or krill. Hence, they are the foundation of the food cycle. Bacteria, like Actinomycetes, decompose decaying matter in soil so that plants and other animals can utilize those nutrients. Microbes are also an important part of the human digestive system. Bacteria, like E. coli, help break down the food we eat Phytoplankton, such as cyanobacteria, are photosynthetic microbes that produce the majority of oxygen on Earth!