Complex sentence: It typically includes the bodies of dead organisms, fragments of organisms or faecal material, and is normally colonised by communities of microorganisms which act to decompose (or remineralize) the material.
Split into simpler sentences: It typically includes the bodies of dead organisms or fragments of organisms or faecal material. Detritus is normally colonised by communities of microorganisms which act to decompose (or remineralize) the material.