A rounded, pillowlike body or mass of sandstone occurring within or just above finergrained sediment or commonly within the basal part of a sandstone overlying shale or mudstone. Its shape approaches that of an elongate, flattened ellipsoid (short axis more or less vertical), and is presumed to have formed by deformation, such as by large-scale load casting or mud flowage accompanied by subaqueous slump or foundering of sand channels.