P Switch

P-Switches (also known as Switch Blocks) are items found in several Super Mario games such as Super Mario Bros. 3, Super Mario World, New Super Mario Bros., and Super Mario 3D Land.

When pressed, a P-Switch makes a change in the stage for a limited amount of time. This includes:
 * Turning Brick Blocks (Used Blocks in Super Mario World) into coins.
 * Turning coins into Brick Blocks (Used Blocks in Super Mario World).
 * Changing enemies into Silver Coins (Super Mario World gray switches only).
 * Turning Munchers and Jelectros into coins (requires gray switch in Super Mario World, but was never used)
 * Allowing Mario to access a hidden door. (Appears as a white light in remakes of Super Mario Bros. 3 and a blue door in Super Mario World. Appears as a normal door in all other games.)
 * Making hidden Coins appear (silver or light blue in many games).
 * Making hidden Question Blocks appear.
 * Stopping conveyor belts from moving (Super Mario Bros. 3)

One rather confusing thing is that a Brick Block with an item inside it will look like a coin, but act like a block. This confusion was removed in the Game Boy Advance remake of Super Mario Bros. 3.

In Super Mario Bros. 3, a P-Switch can cause the animations of Question Blocks, Brick Blocks and Note Blocks to stop. In addition, reversed coins and bricks don't have any animation (except in Super Mario Advance 4: Super Mario Bros. 3).

In Super Mario World, the gray version of the P-Switch makes most enemies turn into Silver Coins. Collecting eight of these coins awards Mario an extra life. Collecting one more gives Mario two extra lives. After nine coins, Mario will earn three extra lives for each additional coin. Also, gray P-Switches can turn Munchers and Jelectros into regular coins. However, this was never actually used in the original game. Super Mario World is the only game in which P-Switches can be carried by Mario and saved for later. (Mario can also carry the switch after it has been pressed for a short time if he's quick before it disappears.) In all other games, Mario can't carry the switches and must use them right where they appear.

In both New Super Mario Bros. and New Super Mario Bros. Wii, some P-Switches could be reused. This is the first instance of P-Switches exhibiting this characteristic. Prior to this, all P-Switches became unusable indefinitely after one activation.

P-Switches appear in Super Mario 3D Land. Here, they are flatter with a light blue "P" printed. When pressed, they become red.

P-Switches also appear in the Nintendo 3DS game New Super Mario Bros. 2, where they serve the exact same functions as in the previous New Super Mario Bros. games.