To quote Fancred member Kirby Hoven: "Contrary to what you might think, this is a Nose Guard."
Today's football position was given its name by the device once adorned by the players themselves.
From the Sports Memorabilia Museum:
"This exceptional piece of vintage football equipment was designed to protect the nose of early football players. The strap of the noseguard went around the head and the was held in place by clenching one’s teeth on a rubber bit. The football noseguard represents one of the more unusual pieces of antique football memorabilia."