Red Shell

Red Shells are red Koopa Troopa shells that first appeared in Super Mario Bros.. Although not their first specific use, they were worn by Koopa Troopas. The Koopa Troopas wearing Red Shells were a bit more intelligent than normal green-shelled Koopa Troopas. They did not fall off cliffs and simply turned around when reaching a ledge. They are second most common shell, after Green Shells.

Similar to a Green Shell, the Red Shell will be launched when the Koopa Troopa wearing it is jumped on. In later games, they can also be held and thrown. In Super Mario Bros. 2 (which calls them "Turtle Shells"), they are the only type of shells and are found in grass rather than on Koopa Troopas.

During the events of Super Mario World, Yoshis can spit out fire while in possession of the Red Shell.

In the Mario Kart series, they can home in on the opponent whose rank is one higher than the driver's. Red shells can be picked up in singles or triples, in which case they circle around the kart until all three are fired. In this state, they can be used as a barrier, useful for blocking contact with other shells (except Blue Shells) and Bananas. If the character comes in contact with any other driver, then the other driver will be knocked over.