Aha! This is cool! I like it. Not sure if explosions or spike balls.I'm gonna help you out. In WW2, most of the surface-to-air weapons fired was 88mm Flak ( i.imgur.com/yF9uNgL.jpg) . When it exploded in air, it was more of a ball of black smoke with a very short explosion that shot tiny shrapnel everywhere. ( i.imgur.com/N4wG47H.jpg i.imgur.com/SfBwEzD.jpg) It was usually used when Allied bomber aircraft were right over their targets, when the German attacking fighters could get away to avoid friendly fire. (And vice versa for the Axis side.)Alright, history lesson's over.