What am I?

I hide in a dark tunnel awaiting my time. I can only be released by pulling back. Once released, I may do unstoppable damage. What am I?

related riddles

To throw me, you’d prefer a crowd what am I?

I go in hard, come out soft. Blow me hard and I’ll make a pop. What am I?

First you see me in the grass dressed in yellow gay; next I am in dainty white, then I fly away. What am I?