What Am I Riddles

Question: I am an instrument that you can hear, but you can not touch or see me.

What am I?

Question: When I'm born, I stay in the sun A little time, and I make crazy When I'm old, I'm worth a fortuneWhat am I?

Question: I have a name that's not mine,
and no one cares about me in their prime.
People cry at my sight,
and lie by me all day and night.

What am I?

Question: I can be used to build castles,
but I crumble in your hands.
I can help a man see,
and am found all around the lands.

What am I?

Question: I'm in everybody but everybody still wants me.
I won't feed you but I'll feed the tree.

What am I?