Red Koopa Shells are shells from red Koopa Troops that frequently appear in various Mario games and have the most impact in the Mario Kart game series. It's the second most common shell after Green Shells. In the Mario Kart series red Koopa shells also known as Torpedo shells made their first appearance in the Super Mario Kart game. They have the ability to lock in on opponents in front of the player making them a very powerful weapon against opponents. Red Koopa Shells also appear in sets of three and can be stolen by opponents by using a Boo ability, which not only makes the user transparent, but also allows him to steal opposing players' items. A fanart Mario progress bar for YouTube with Red Koopa Shell.