Key

There are dozens of different keys for castles and fortresses all across the Mushroom World.

In Super Mario Bros. 2 keys were used to, of course, get into locked doors. Phantos will always be guarding keys, so once you have a key, RUN!!! Unless you toss the key or unlock a door, a Phanto will always be chasing you. Keys are usually either in a pipe, or in a room with a massive Phanto mask on the wall. Don't bother plucking every vegetable to find one, they're always in view.