Answer:
If you are to keep it, you must first give it to me. What is it?
I can be found in seconds, minutes and centuries, but not in days, years or decades.
It is a form of plastic money.
What object has keys that open no locks, space but no room, and you can enter but not go in?
Ancient and majestic, great big piles of stones, Used to encase both riches and bones. Seen from certain angles, They look like big triangles.
It flows out of the soil, It burns you if it boils, And holds us in its coils, More valuable than gold, As black as it is old.