Woody detritus is an important component of forested ecosystems. It can reduce erosion and affects soil development, stores nutrients and water, provides a major source of energy and nutrients, and serves as a seedbed for plants and as a major habitat for decomposers and heterotrophs.
Source: wiktionary
It is likely that the long evolutionary trajectory of Mycoplasma went from a reductive autotroph to oxidative heterotroph to a cell-wall–defective degenerate parasite. This evolutionary trajectory assumes the simplicity to complexity route of biogenesis, a point of view that is not universally accepted.
Source: wiktionary