"Ice-nine" is an alternative structure of water that is solid at room temperature and becomes a seed crystal in contact with any liquid water, causing that liquid water to instantly transform into more "ice-nine".Among some odd unfoldings in Ilium, the narrator meets Hoenniker's younger son, a dwarf named Newt, who recounts that his father was doing nothing more than playing the string game "cat's cradle" when the first bomb was dropped.