This is distinct from classes such as http://purl.obolibrary.org/obo/UBERON_0001988 in that it refers to the environmental material composed primarily of feces rather than 'just' feces.

An excreta material which is composed primarily of feces, an excreta consisting of waste products expelled from an animal's digestive tract through the anus (or cloaca) during defecation.

ENVO bodily fluid classes differ from UBERON's treatment of bodily fluids. UBERON refers to the substance itself ("S"). We assert that UBERON's classes are the primary compositional component of the terms in ENVO ("S material"). Use of the ENVO terms is typically recommended when you wish to indicate that there may be other materials intermixed with S.