fiberglass are usually tongues of sound age in elevation
fiberglass is fibrous_thing. fiberglass is glass. wineglass is glass. fibreglass_wool_batting is glass_wool. glass_wool is fibreglass. hourglass is sandglass. hourglass is ancient_form_of_measuring_time. fibreglass_batting is glass_wool. hourglass is old_way_of_telling_time.