Answer:
You throw me out when you want to use me and you take me in when you don't want to use me. Who am I?
My first is in fish but no in snail. My second is in rabbit but no in tail. My third is in up but not in down. My fourth is in tiara but not in crown. My fifth is in tree you plainly see. My whole a food for you and me.
Break it and it is better, immediately set and harder to break again
What can go through glass without breaking it?
What word looks the same upside down and backwards?
I am the fountain from which no one can drink. For many I am considered a necessary link. Like gold to all I am sought for, but my continued death brings wealth for all to want more.