Box Spring

From the Super Mario Wiki
BoxSpring.png

Box Springs are objects in Mario vs. Donkey Kong: Minis March Again!, introduced in Sandstone Stroll. They are contained in flashing green blocks found on the ground. When the player taps on a Box Spring on the touchscreen, it briefly releases a Yellow or a Blue Spring that can bounce up any mini that walks over it. The type of spring is shown on the block itself.