AsciiMan Cave generation

To the left you can see a cave generated by the game, my method starts with a grid filled with random bools, I then apply the CA (cellular automaton), as of time of writing, 15 times. The CA is as follows:
If a square has less than 4 surrounding walls it becomes a floor, if it has 4 it stays the same, if it has more than 4 it becomes a wall.