Bombshell Koopa

Bombshell Koopas were thought up to replace Koopa Troopas in the Game Boy's Super Mario Land because the device's computer limitations rendered it impossible to create the sliding shell effect. Instead, when stomped, the Bombshell Koopa retreats into its shell, waits for 2 seconds, and explodes. This is a very common enemy, to make up for the total lack of regular Koopas.