#N Hammerhead
#C An orthogonal period 4 c/2 spaceship with many different possible rear ends.
#C www.conwaylife.com/wiki/index.php?title=Hammerhead
x = 18, y = 16, rule = 23/3
5o13b$o4bo7b2o3b$o11b2ob3o$bo9b2ob4o$3b2o3b2ob2o2b2ob$5bo4bo2bo4b$6bob
obobo5b$7bo10b$7bo10b$6bobobobo5b$5bo4bo2bo4b$3b2o3b2ob2o2b2ob$bo9b2ob
4o$o11b2ob3o$o4bo7b2o3b$5o!