The following p4 c spaceship with a minimum population of 28 cells. Compare accidental puffer.

accidental ship.png

x = 13, y = 12, rule = s0/b2
6bo4bo$o6bo4bo$8bo3bo$o9bo$4bo4bo$5b3o$5b3o$4bo4bo$o9bo$8bo3bo$o6bo4bo
$6bo4bo!