In biology, detritus is dead particulate organic material (as opposed to dissolved organic material). It typically includes the bodies or fragments of dead organisms as well as fecal material. Detritus is typically colonized by communities of microorganisms which act to decompose (or remineralize) the material. In terrestrial ecosystems, it is encountered as leaf litter and other organic matter intermixed with soil, which is referred to as humus. Detritus of aquatic ecosystems is organic material suspended in water and piles up on seabed floors which is referred to as marine snow.