Answer:
I have been the beginning of ideas for all time yet I am just one simple small object the things that you can use me for can be frustrating and also I can be pretty. I have some of the most valuable thing in the world on me yet almost everyone owns me.
My rings are not worth much, but they do tell my age. What am I?
I am a busy worker who is a water mammal.
I love spinach.
What loses its head in the morning but gets it back at night?
No matter how little or how much you use me, you change me every month.