The Monty Tank is the World 6 boss in New Super Mario Bros. for the Nintendo DS. The green tank is operated by a Monty Mole that fires Bullet Bills. He is in the castle at the end and after defeating him the player will move on to World 8 in pursuit of Bowser Jr. who takes Peach deep into the lava world. The Monty Tank is the main boss if the player didn't defeat Petey Piranha as Mini Mario and didn't progress to World 7 instead of World 6. Otherwise, the boss would be Lakithunder.