Mochi is a weird sticky substance that clumps together. It will stick to whatever touches it, unless it becomes too heavy. In Levels, it will stick to the user and allow it to fly, or it will swallow the user whole. When mixed, it can make objects sticky or hard to break apart. It doesn't melt, burn or boil, or put out fires. When drawn in a line, mochi snaps back and is amusing in Zero-G. It reacts violently with Jet, creating many high-energy compound particles.
Mochi is the name of a cake made from combining gelatinous rice and water and adding pressure. See Wikipedia for more info.