Green cemeteries and natural burial grounds require that green caskets or a shroud be used when the body is buried, and prohibit the use of outer burial containers. This helps to maintain the natural habitat of the environment, including maintaining clean groundwater, preserving the natural landscape, and providing an environment for native plants and animals to thrive. Conventional cemeteries often use herbicides to maintain the grass, which can be absorbed into the earth; outer burial containers, which impede the decomposition of the body and take an extremely long time to decompose; and allow embalmed bodies to be buried, which results in formaldehyde and other embalming chemicals to enter the earth.