I have two butts, I kill a lot. What am I?

I appear in a jar, but I am not a liquid. You might see me in The hand of a monster!.

I'm spiky and proud, a fruit with a flair, but people smell me and dive for fresh air. I taste like dessert, but reek like a crime, a feast or a fart, who's to say?

I'm a breeze that needs no wind, A song without a tune. I arrive uninvited, Gone way too soon.

What has many keys but can’t open a single lock?