x = 37, y = 10, rule = B3678/S34678
3b2ob2o$2bob3obo5bo3bo$bob5o4b5o$ob6o2b8o$19obo4b2o8b2o$19obo4b2o8b2o$
ob6o2b8o$bob5o4b5o$2bob3obo5bo3bo$3b2ob2o!
A period 20 block-puffer.
Multiple copies of this can be combined to produce other puffers
and spaceships.
Mark D. Niemiec, April 1997