Giant Red Shell

From the Super Mario Wiki

Giant Red Shells are Items found in many of the Mario games. In Super Mario Bros. 3, the red shelled Gargantua Koopa Troopas wear these giant shells, instead of wearing normal Red Shells. These large Koopas would not walk off the edge, unlike the Gargantua Koopas with Green Shells. Instead, they would turn around, and walk on solid ground. Mario could simply jump on these oversized Koopas, and they would hide in their shell, just like a normal Koopa Troopa. Mario could throw these shells, which will then smash into other enemies.

In Super Mario Strikers and Mario Strikers Charged, Giant Red Shells, as well as their smaller counterparts, are items that players can use. When collected, Giant Red Shells could be shot at the opposing players. It would then home into one of the opposing team members, and spin over him/her, which will squish them, thus, knocking them out for a short while. However, it will only home in once, and after it hits its target, it will just spin around the stage randomly, unlike the normal Red Shells, which home into multiple players, but only hit once.

Mario Strikers Items
Banana | Giant Banana | Green Shell | Giant Green Shell | Red Shell | Giant Red Shell | Blue Shell | Giant Blue Shell | Spiny Shell | Giant Spiny Shell | Bob-omb | Giant Bob-omb | Chain Chomp | Mushroom | Star

Shells
Green Shell | Giant Green Shell | Red Shell | Giant Red Shell | Triple Shells (Green · Red) | Blue Shell | Giant Blue Shell | Yellow Shell | Spiny Shell (Mario Kart) | Giant Spiny Shell | Black Shell | Bowser's Shell | Gold Shell