The odour of decaying corpses could be smelled up to away. Corpse farms are also used to study the interactions of insects with decaying bodies. Many scarabs are scavengers that recycle dung, carrion, or decaying plant material. Acidic water, which can result from decaying vegetation, dissolves limestone. Then filled in with mud, sediment, feces and decaying vegetation. Freshwater on the island may become stained by organic acids found in decaying vegetation. These beetles evolved to consume decaying wood in forested habitats. Females lay their eggs in a piece of decaying wood deep in the soil. Soil organic matter is a mix of decaying material from biomass with active microorganisms. Organosulfur compounds are responsible for some of the unpleasant odors of decaying organic matter. Honey fungus can grow on living, decaying, and dead plant material. Earthworms eaten by robins are detritivores consuming decaying leaves. The larvae feed on decaying organic tissue. Foxfire is the bioluminescence created by some species of fungi present in decaying wood. In modern humans, necrophagy (eating of dead/decaying flesh) occurs rarely in most societies.