Answer:
I cost no money to use, or conscious effort to take part of. And as far as you can see, there is nothing to me. But without me, you are dead.
Two brothers we are, great burdens we bear. All day we are bitterly pressed. Yet this I will say, we are full all the day, and empty when go to rest.
Halo of water, tongue of wood. Skin of stone, long I've stood. My fingers short reach to the sky. Inside my heart men live and die.
I build up castles. I tear down mountains. I make some men blind. I help others to see.
Although I'm not an insect, some people found me very difficult to exterminate. They called me something like 'insane priest.' The first half of my name means the same as 'scrape,' & my last three letters are a metal. Who am I?
Within, I clean all that is bad and is old. I make juice thatβs the color of gold. Should I die, a filter machine would you need assembled to replace me and beans I resemble.