`x = 4, y = 4, rule = B34e/S23`

b3o$o2bo$o2bo$3o!

EDIT: Rule with not only a puffer, but a quadratic replicator, as well as some other interesting patterns:

`x = 35, y = 20, rule = B34w/S23`

31bo2bo$31bo2bo$32b2o14$30bo$bo5bo21b3o$2o5b2o19b5o$bo5bo19b3ob3o!

A rule that has a p9, and has slightly more eaters:

`x = 3, y = 4, rule = B3-r/S23`

3o3$3o!

`x = 3, y = 5, rule = B3-r/S23`

2o$3o2$2o$2o!