From wikipedia:

Langton's ant is a two-dimensional universal Turing machine with a very simple set of rules but complex emergent behavior. It was invented by Chris Langton in 1986 and runs on a square lattice of black and white cells.

1. Start the ant on a random point in the grid.

2. On each move, check the color of the square the ant is currently on and do the following:

   3. Depending on the current square's color, turn the ant 90 degrees to the right or turn the ant 90 degrees to the left.
   4. Change the color of the current square from white to black.
   5. Move ant forward one square, in the direction it is facing.

• start the simulation on command
• pause/resume the iterator

MIT