Nuju had barely realized that when he saw something much more frightening--a huge crack traveling up the side of the tower.  The whole structure was about to fragment and take the Matoran with it.

Nuju got a running start and leaped off the tower.  Using his crystal spikes, he swung from one chute to the the next as fast as he could.  When he was almost at the top of the tower, he let go and dropped.

For once the Toa of Ice tried not to think about the future.  If he pondered the possible consequences of what he was about to do, he would never be able to do it.  He waited until his fall had brought him almost parallel to the crack in the tower, then held out his twin spikes and focused his ice powers though them.  Thin streams of ice shot from the tools, welding the crack shut as he fell.

Now came the hard part. Most of the damage was repaired, but if he could not stop his fall, he would be an ex-Toa Metru very quickly.  He spun, twisted, and dug one spike into the side of the tower.  It carved a gash in the crystal, and he continued to fall, desperately trying to hang onto the Toa tool. Finally with the ground much to close to comfort, the spike held and he came to an abrupt stop.

"No wonder we had to be chosen to be Toa Metru," he thought as he began the long climb to the top of the tower.  "No one would ever volunteer for this job"

~Greg Farshtey, Mystery of Metru Nui, pg 80-81