This is a random question and I'm not scientifically oriented (which is obviously why I'm posting here). If the origin of 'fossil' fuels as we know them came from the leftovers of biological species, why is 'fossil' fuel not called 'tree' fuel? Sure it sounds stupid, but there have been trees, plants, and vegetation on the earth probably much longer (or equally as long) as most animal/insect lifeforms. Not only that, but generally speaking (and before humanity shat all over the planet) trees and vegetation covered nearly everything. I would imagine there have been A LOT more trees and vegetation that has grown/died throughout the earth's history than any kind of biological life form. I'm not questioning the concept of biotic oil origins, I'm merely curious as to why they're called 'fossil' fuels. As for the theory of abiotic oil origins, while I'm skeptical of it, I'd be interested in knowing more about any results found. Thanks in advance.