Brian's Brain, created by Brian Silverman, is a cellular automaton that mimics excitable systems like neurons. Each cell can be in one of three states: On, Off, or Dying. If a cell is On, it transitions to Dying, then Off, and if it's Off, it can turn On if exactly two neighbors are On. The resulting behavior is chaotic yet self-sustaining, with pulsing patterns that resemble waves of activity spreading across the grid.