Antimatter appears to be a collection of transparent shapes, including a purple, green, and yellow triangle as well as a pink/red jagged shape. He also has a jagged mouth, and has colored limbs that they can retract or expand. Antimatter is shown to be somewhat snooty, and can also get cocky sometimes. Antimatter is also the second most-powerful character. They say they can "essentially do anything". He also can see 9 dimensions, and can manipulate their size