AckStack

Acks are insect-like enemies that appear in the Wii game Donkey Kong Country Returns. They, along with Cageberries and Toothcherries, are sub-species of Toothberries. They are yellow enemies with fangs. Acks are found in groups of five, and each one of them are piled on top of each other, trying to harm the Kongs. Their stack is known as the "Ackstack". If Donkey Kong gets too close to them, they will fall with their mouths open, attempting to defeat him. However, if Donkey Kong jumps back, dodging the monsters, they will land separate from each other. When single, Acks are vulnerable to jump attacks. On a side note, the Kong Roll has no effect against the Ackstack, but the Kongs won't get injured for attempting this maneuver.