Koopa Shell (Mario)

Koopa Shells are the shells worn by Koopa Troopers in the Super Mario Bros. series. They are generally obtained by jumping on a Koopa Trooper, making them hide or pushing them out of it. They can then be kicked to break blocks or attack enemies, although if it bounces off a wall and hits the player, it counts as a hit. It is only removed from play if it collides with another Koopa shell, or is hit by a fireball from a Fire Flower. Super Mario Bros. 3 introduced the ability to pick up Koopa Shells by holding the dash button, and throwing them either forwards or upwards.

Super Mario Bros.
These have the basic kicking rule applied. The shell colour represents the Koopa Trooper's behaviour. Red shelled troopers would stick to a platform, whereas Green-shelled troopers walked off platforms, only changing direction when walking into a wall.

Super Mario World
In this game, Koopa Trooper's were kicked out of their shells if jumped on. Certain properties were given to the shells, particular if grabbed whilst riding a Yoshi. Since Yoshi can't swallow Koopa shells, these are spat out. Green shells act the same as being thrown whereas Red shells came out as three multi directional fireballs. Holding a Blue Shell in Yoshi's mouth temporarily allows Yoshi to fly. Another shell, should a Koopa Trooper enter it, makes it spin violently and home in on the player.

Mario Kart (series)
There are three types of shell in the Mario Kart series. The Green shell fires in a single line and bounces off walls until it hits a driver. This can be fired forwards or backwards, and can also be used for defense. The Red shell homes in on the nearest enemy, but stops if it collides with a wall. The green and red shells are either obtained as a single item, or a rotating shield of three, which can also be used as a defense, or attack enemies that touch them. The blue shell zooms ahead to the front of the track and attacks the player in 1st position, creating a giant explosion stopping him and anyone else caught in the blast.

Super Mario 64
Jumping onto a Koopa shell makes Mario ride on it for a short time. As well as being able to knock out small enemies, he can ride on the surface of water or lava.

Super Smash Bros. (series)
In the Super Smash Bros. games, there are two shells. They can be activated by either throwing or jumping on them. The green shell fires straight, hurting opponents who hit its sides, but can be stopped if jumped on again. The red shell, once activated, homes in on enemies on the platform it landed on, launching anyone who touches it, including whoever threw it.

New Super Mario Bros.
A Blue Koopa suit can be worn by Mario, allowing him to curl up into a Koopa shell whilst running. This makes him attack weak enemies, but also makes him bounce off walls. Getting hit in this form reverts him to Super Mario.

Super Mario Galaxy
Koopa shells have two functions in Super Mario Galaxy. The first is as a projectile, with green shells firing straight forward and red shells homing in on opponents. These can be used to open chests or attack far away enemies. The second acts as an underwater vechile, complete with headlights amd brake lights which travels faster than normal swimming. The red shell has more speed in this aspect. These can also be fired by shaking the Wii Remote. A golden shell is included in some levels, usually required to complete an objective.