Decomposers get their food by breaking down dead plants and animals and the waste products of the dead organisms. The process is called Decomposition. When organisms die, their remains are disintegrated into smaller and smaller fragments by the decomposers. At the end, the complete body is decomposed into the soil. That is how the nutrients and minerals are recycled in nature. Thus, these organisms help us maintain a balance in nature.
Certain bacteria and fungi belong to this category.