Primary producers use energy from the sun to produce their own food in the form of glucose, and then primary producers are eaten by primary consumers that are in turn eaten by secondary consumers, and so on, so that energy flows from one trophic level, or level of the food chain, to the next. These microorganisms called decomposers break down the complex organic matter into simpler inorganic substances like CO2 water and nutrients. Decomposers are organisms that decompose the remains of dead plants and animals to aid the recycling of matter.