What Am I Riddles - 2

Try solving these What Am I riddles. Then check the answers at the end of the questions. Enjoy!

1. I am a box that holds keys without locks, yet my keys can unlock your deepest senses. What am I?
2. A box without hinges, lock or key, yet golden treasure lies within. What am I?
3. I am lighter than a feather, yet no man can hold me for very long. What am I?
4. Feed me and I live, give me something to drink and I'll die. What am I?
5. I can be long, or I can be short.
   I can be grown, and I can be bought.
   I can be painted, or left bare.
   I can be round, or I can be square.
   What am I?
6. I am an insect and the first half of my name reveals another insect.
   Some famous musicians had a name similar to mine.
   What am I?
7. You heard me before,
   Yet you hear me again.
   Then I die, 'til you call me again.
   What am I?
8. Who makes it, has no need of it,
   Who buys it, has no use for it,
   Who uses it can neither see nor feel it.
   What is it?
9. It cannot be seen, it weighs nothing, but when put into a barrel, it makes it lighter. What is it?
10. Forward I'm heavy, but backwards I'm not. What am I?

Answers

1. A piano
2. An egg
3. Your breath 
4. Fire
5. Fingernail 
6. Beetle
7. An echo
8. A coffin
9. A hole
10. A ton