Matter and energy cycle through the living and nonliving parts of the ecosystem in the form of chemical compounds. Some chemical compounds make up living organisms that are called 'organic compounds'. Chemicals in the ecosystem are recycled. Some of the organic compounds of living organisms are returned to the ecosystem. Some of the organic compounds make up dead organisms. Some organic compounds are returned as nutrients to the ecosystem. Dead producers and consumers provide matter and energy to decomposers. Dead decomposers recycle dead matter, and the dead matter is returned to the ecosystem. All matter and energy are then returned to the ecosystem in one way or another. The matter and energy of the ecosystem can be recycled indefinitely because it is constantly being produced and consumed.