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A Kuromame (クロマメ, lit. Black Bean), also known as a Keronpa Ball (ケロンパボール, Keronpa Bōru), is an obstacle found solely in Super Mario 64. They are tiny black spheres that hover in place a tiny distance off the ground. They usually line the edges of pathways. A Kuromame is motionless and harmless until Mario passes by. Then, it expands to about twice its size and shoots a tiny fireball that chases Mario around for a short time until it goes out. If hit by the flame, Mario will run around uncontrollably while steadily losing three life pieces, although he will still be able to jump.
There are two Kuromame located in the downtown area of Wet-Dry World. Due to a mistake in the level design, however, they cannot spit fire. Even at its shallowest point, the water level in the area is high enough that the two Kuromame are submerged, rendering them harmless. They can be activated using glitches, though. By using the water-raising/water-lowering glitch, the water can be made to go lower than normal, so they can be activated.