Green Shell
Green Shells are green Koopa Troopa shells that first appeared in Super Mario Bros.. These are the most common type of shell. Koopa Troopas wearing Green Shells were less intelligent than their red shelled counterparts. They would fall off cliff if they reached the ledge.
Similar to a Red Shell, the Green Shell will be launched when the Koopa Troopa wearing it is jumped on. In later games, they can also be held and thrown.
Green Shells could be ridden in Super Mario 64. When a character jumps atop a Green Shell, the character can travel at a fast speed. It also allows the character to cross over unwalkable terrain, like lava or icy water.
In the Mario Kart Series, Green Shells will shoot forward in a straight line. Unlike the red shell the green shell is able to ricochet off of walls. After about five ricochets, the Green Shell will automatically disappear. Green Shells also come 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, the the other driver will be knocked over.
Green Sheels also appear in the Super Smash Bros. Series. A Green Shell is a regular item which can be picked up and thrown at other characters, hurting them. It can also be activated by hitting it or jumping ontop of it, which causes it to shoot in a certain direction, knocking out any characters on the way.