Coin counters, also referred to as Mushroom Coins or Coin icons, are objects that appear exclusively in the Super Mario Advance series. They are large yellow hexagonal blocks imprinted with the image of a regular coin on each. When a coin counter is hit, it displays how many coins are left, and it counts down, rewarding the player if the required coin number is collected.
In Super Mario Advance 4: Super Mario Bros. 3, Mushroom Coins appear in completed save files. A Mushroom Coin appears at the beginnings of the stages that can unlock White Mushroom Houses, and it displays the number of coins necessary to unveil it on the bottom left corner when hit. One also appears in the World-e level Bombarded by Bob-ombs, where it gives three extra lives for collecting 110 coins.
- Nintendo Power Advance v.4, page 26. "COIN COUNTER There is a total of 600 coins in the bonus area. The coin counter atop the first set of pipes will help you keep track of how many remain."
- Hodgson, David S J. Super Mario Advance 4: Super Mario Bros. 3 Prima's Official Strategy Guide. Page 24. "TOAD'S WHITE MUSHROOM HOUSE Toad also has a hidden house that he reveals only to highly skilled plumbers! In each of the first seven worlds, one of the stages has a different type of Mushroom Coin, floating at the stage′s beginning. Grab it if you want a chance at accessing the White Mushroom House. Information appears in the screen′s bottom-left corner showing the number of Coins you must collect before you finish the level. Collect them all, and the White Mushroom House appears."
- Hodgson, David S J. Super Mario Advance 4: Super Mario Bros. 3 Prima's Official Strategy Guide. Page 122. "Coin Kidding Take the Coin icon, and you see you have 110 Coins to find! This is very difficult, as you must reach each 10 Coin Block immediately and strike all 10 Coins out to gain all the Coins. The reward is only three 1Ups, so don't worry about completing this task."