Answer:
I go up when the rain comes down
I am a mountain at night, meadow at day. What am I?
What is made of wood, but can't be sawed?
I am a kind of coat that can only be put on when wet. What am I?
It's been around for millions of years but is never more than a month old. What is it?
Give it food and it will live, give it water and it will die.