the.com/clay pigeon

means A saucer-shaped target, usually made of pitch and limestone, flung into the air by a trap machine for shooters to blast apart with a shotgun.

from Despite the name, it was never clay. Early trapshooters in the 1800s used live pigeons (hence 'trap shooting'), but as that fell out of favor, inventors cast glass balls and later pitch-and-dust discs to mimic a bird's flight. The name 'clay pigeon' stuck purely out of nostalgia for the original target — a label that outlived the thing it described.