The organisms which breakup the dead bodies of animals and plants into smaller parts.
Imagine this scene... bodies are piled high, everything from birds and mammals to lizards and frogs. Mixed in are leaves, branches, feces, and even dead people. The stench is overwhelming. You try to turn away, but you are surrounded. It sounds like a horror movie, but at this show, you can't even have a grilled cheese sandwich with a glass of wine while watching the horrors unfold. Where are you? In a world without decomposers.
It may be unpleasant to think about, but decomposers do the natural world's dirty work. They are responsible for eliminating dead and dying organisms, and in the process, they release nutrients into the soil.
Job Categories of Living Organisms
There are three categories of jobs that living organisms have in the environment. Producers are green plants that produce their own food using the sun's energy. Consumers need to eat other living things, such as plants or animals (or both), to get their energy. Decomposers have the job of 'recycling' dead organisms and waste into non-living elements.
Examples of decomposers include bacteria, fungi, some insects, and snails, which means they are not always microscopic. Fungi, such as the Winter Fungus, eat dead tree trunks.
Decomposers can break down dead things, but they can also feast on decaying flesh while it's still on a living organism. Dung beetles, as you may have accurately concluded from their name, break down feces from other animals. Some decomposers, like snails and worms, can also be consumers because they sometimes eat plants.