Detritus refers to distinct particles of dead organic material combined with some microorganisms that feed on it. When plants and animals die for example, part of them will remain and decompose with the assistance of microorganisms. This leftover material or particle will settle in the soil, on sea beds or even float in water. This specific remains or particle is referred to as detritus and many of it gets re-mineralized because of the presence of microorganisms. In many cases, the feces from small animals that feed on these dead particles contain a mixture of dead material and various microorganisms making it a type of detritus.

For some animal species, detritus serves as a food source. This is especially true for the so-called bottom dwellers. Small animals or microorganisms that stay at the bottom of the sea or river for example feed on these left-over material called detritus. Even if the main components are dead tissue or material, these remain organic and become a good source of nutrients for many microorganisms. These microorganisms will then help detritus to decompose and get re-mineralized. The remaining particles may either get mixed up with other particles and substances while some will settle in their environment and continue to decompose or get eaten by other microorganisms.

Detritus may have dead plants or animals as components but it contributes to an important cycle in biology enabling some microorganisms to survive and get food. Once the decay starts for some dead plants and animals, the detritus cycle will start with the help of microorganisms that feed on them. The dead particles will then get re-mineralized and become an organic food source for other microorganisms. After they get eaten or consumed, detritus will then be excreted and become a renewed food source once again for the benefit of other organisms which re-starts the cycle.