Where did oil originally come from?

Related questions

1. Do oil prices go down in summer?
2. Does US buy oil from Saudi Arabia?
3. Who is the owner of oil company?
4. Can the world run out of oil?
5. Why are oil prices declining?
6. How much does oil cost?
7. When oil prices go up what happens?
8. How was oil created?
9. What was the price of oil in 2011?
10. How oil prices are decided?

Tags

1. #remains
2. #millions
3. #bottom
4. #animals
5. #marine
6. #petroleum
7. #comes
8. #years
9. #plants
10. #organisms
11. #dinosaurs
12. #notion
13. #before
14. #formed
15. #crude
16. #lived
17. #fiction
18. #surprised