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 hazards, such as Bananas. However, they offer no protection against Blue Shells and Fake Item Boxes. If the character comes in contact with any other driver, then the other driver will be knocked over. The exception to this rule is in Mario Kart: Double Dash!!, where the shells are carried rather than circle around a character's kart. In Mario Kart DS Wi-Fi mode, they could not be dragged by holding the item button.

Red Shells also appeared in the Super Smash Bros. Series. They were in both Super Smash Bros. and Super Smash Bros. Melee. Unlike the Green Shell, which went in a straight path until it fell off, the Red Shell will stay on one platform, and bounce back and forth hitting anyone who hits it (including the user). They disappear over time, however. Notably, the Red Shell is absent from Super Smash Bros. Brawl.

In the Mario Strikers soccer game series, the item works very similarly to the Green Shells, which are also found in the games, however, they differ slightly in appearance and effect. They are red, and instead of moving in one direction, they home in on the opposing players. Everytime this item is collected, it will be collected in a group of three. This allows it to home in on three opposing players, however, one will not get hit. These can be used when trying to perform a Mega Strike, or a Skillshot. There is also a very small chance that the shells might miss the opposing team members, and start bouncing around the stage like a Green Shell. The giant variety of this shell also appeared in the games.

Red Shells reappear in Super Mario Galaxy as an offensive weapon. Like the Green Shells in the game, Mario can only hold the Red Shell, not ride it. If Mario throws the Red Shells near an enemy, it will home in that enemy until it hits something. Underwater, it allows Mario to swim faster and with greater ease. It can also be thrown at underwater creatures and home in on them as well. The other variety of shell that appear in Super Mario Galaxy are Gold Shells, which act like Red Shells when thrown.

Trophy Information
''Throw a Red Shell, and it will home in on random characters and send them flying straight up. Red Shells moving around the surface are dangerous to all players, but they may also present attack chances for players with good timing and strategy. Red Shells won't leave the platform they're on once they start moving.''