Brian's Brain

Each cell is considered to have eight neighbors (the Moore neighborhood), as in Seeds and Conway's Game of Life.

In each time step, a cell turns on if it was off but had exactly two neighbors that were on, just like the birth rule for Seeds.

Because of the cellular automaton's name, some websites compare the automaton to a brain and each of its cells to a neuron, which can be in three different states: ready (off), firing (on), and refractory (dying).

[1][2] The "dying state" cells tend to lead to directional movement, so almost every pattern in Brian's Brain is a spaceship.

For example, a 2×2 block of on cells will result in an ever-expanding diamond consisting of four diagonal waves that move across the plane at the pattern's speed of light.