It has a tendency to roll and has a unique number that is determined upon how many times its gift has been opened before.
According to Defaultio, the balls are an economic experiment to see if players would trade for balls with certain numbers. The ball number continues to increase every opening.
Both the Red Ball and all of its counterparts will not go up a Tilted Conveyor unless a player, log/plank, or dynamite pushes it. A report stating a player having two balls of the same number has been cited. The report has never been heard of ever again.