Answer:
I build up castles. I tear down mountains. I make some men blind, but I help others to see. What am I?
You use me between your head and your toes the more I work the thinner I grow.
I have a neck but no head. I have a body but no arm. I have a bottom but no leg. What am I?
Good memory, skin like the sea. A great beast I am, yet vermin frightens me. What am I?
I help boats park
I am owned by Old McDonald.