The brain of the bonassi continually sends messages to the rest of its body telling it to move all of its muscles at the same time. Muscles usually work in pairs, for example one muscle will be responsible for pushing, whilst the other is responsible for pulling. However the bonassi try to move both at the same time and so their bodies simply vibrate. This continuous vibration travels down through their tails and makes them ideal creatures for breaking up rocks. This potential affliction turns out to be extremely useful in the mines of Zelk. Happy days.