#shell.housing__case__casing  the housing or outer covering of something; "the clock has a walnut case"
  supertype:  housing.protective_cover  a protective cover designed to contain or support a mechanical component
  part of:  grandfather_clock
  subtype:  boot.shell  protective casing for something that resembles a leg
  subtype:  gearbox__gear_case  the shell (metal casing) in which a train of gears is sealed
  subtype:  jacket.shell  the tough metal shell casing for certain kinds of ammunition

No statement uses or specializes shell.housing; click here to add one.