The Thing That Grows Without Being Alive

Riddle:

I am not alive, but I grow. I don’t have lungs, but I need air. I don’t have a mouth, but water kills me. What am I?

Answer:

Fire – Fire needs fuel and oxygen (air) to grow. It’s not alive biologically, yet it “behaves” as if it is. Water extinguishes it. The riddle uses anthropomorphic metaphor.