Green Shells first appear in Super Mario Bros.. After a Koopa Troopa is hit by a jump attack, it will retreat into its shell, leaving it for Mario to use it. Upon contact, the shell is launched, defeating every enemy in its way. However, this can also backfire when the shell rebounds from any obstacle. A shell in motion can be stopped by stomping on it. If a Koopa Troopa is seen wearing a Green Shell, that means that it will not turn around if it reaches a cliff and will instead straightly walk into it. The Koopa Troopa will stay in the shell for only a limited amount of time. After a while, the Koopa Troopa will get out of its shell and resume its business. Koopa shells could only get destroyed by a fireball shot by Fire Mario or a Starman from Rainbow Mario.
