This figure is a "period 256 rocket gun which demonstrates the symmetry of the Day/Night rules, and how a signal can be sent across the border between day and night regions. Here a period 256 anti-gun destroys every other rocket from a normal period 128 rocket gun. Based on a reaction by Dean Hickerson." David I. Bell, May 1997 Legend :

• Green : cell that comes alive at this iteration. Shade indicates how many of the cell's neighbors are alive : darkest green indicates only 3 alive neighbors, lighter greens indicates more alive neighbors, up to 8 alive neighbors indicated by the lighest shade of green.
• Yellow : cell that stayed alive at this iteration. Shade indicates how many of the cell's neighbors are alive : darkest yellow indicates only 3 alive neighbors, lighter yellows indicates more alive neighbors, up to 8 alive neighbors indicated by the lighest shade of yellow.
• Black : dead cell.