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Coin Stacks are items that first appear in New Super Mario Bros. 2, although only in the title screen. Coin Stacks first appear as collectible items in Super Mario 3D World. Coin Stacks are ordinary Coins that are stacked up in piles that each have different amounts; the coins act as they normally do, giving an extra life for collecting 100 of them. Coin Stacks can be found in hidden areas of levels, like in the underground area of Really Rolling Hills. They are a very common item in the bonus level Coin Express, where they appear alongside of Coins, Coin Rings, and Gold Shells.
Coin Stacks reappear in Captain Toad: Treasure Tracker, acting as they did in Super Mario 3D World.
Coin Stacks appear in Super Mario Odyssey, acting as they did in Super Mario 3D World. Large amounts of coin stacks can be found in certain hidden or secluded areas. After they have been collected however, they will be replaced with smaller stacks worth only 15 coins if Mario returns to the area. They can also come out of bushes, causing them to bounce along the ground in an erratic fashion, like Super Stars. Once they bounce into water, or if they bounce for too long, they disappear. These stacks are worth 10 coins.