The Four-layered Sugar Chest is a blocker in Candy Crush Saga, making its first official appearance in level 711. However, it is unofficially introduced, both as starting configuration and appearance, in level 501.
Four-layered sugar chests are single-tile stationary blockers that take four matches involving sugar keys to open and therefore destroy. Each matched sugar key results in a degrade. After the first degrade, it becomes a three-layered sugar chest with only the pink icing layer, then after the second degrade, becomes a two-layered sugar chest with a crumbly biscuit topping, then after the third degrade, becomes a sugar chest with no toppings. These blockers cannot be destroyed by anything other than matches involving the sugar key.
Here is the difficulty of destroying a four-layered sugar chest: