There would be dead animals overloading the Earth. Think about it, without worms and other things that break down dead things they would still be here and just sit there.
They move from an area of higher concentration to an area of lower concentration or they move down the concentration gradient
The place where an organism lives and that provides the things it needs to survive is its habitat.
Many things don't come from petroleum.
-Crunchy Peanut Butter
-Red Delicious Apples
-Pink Quartz
-Wool Tube Socks
For a more specific answer, it would be best to ask a more specific question.