3 ms·Unlike rocks, plastic is high in energy (as evidenced by the fact that you can put it on fire).by jaggirs 4y agoUnlike rocks, plastic is high in energy (as evidenced by the fact that you can put it on fire).salamo 4y agoSure, but petroleum is also high in energy. There are even some bacteria that consume it. Yet petroleum is still available in huge deposits.kevviiinn 4y agoDeposits are the key, it generally isn't readily available on the surface where most of the living organisms are