Saprotrophs are living organisms who obtain their nutrition from non living organic materials.

E.g.

Fungi:

Fungi decompose cellulose materials by their extra cellular enzymes into carbohydrates and releases the carbon dioxide from decaying organisms, which helps in maintaining the carbon cycle for ecosystem.

Bacteria:  Escherichia coli, acts as a decomposers of dead organisms and breaks down the animal tissues into small organic molecules.