Charles Darwin showed that it was the action of earthworms. He actually wrote a book about this: https://en.wikipedia.org/wiki/The_Formation_of_Vegetable_Mould_

Charles Darwin showed that it was the action of earthworms. He actually wrote a book about this: https://en.wikipedia.org/wiki/The_Formation_of_Vegetable_Mould_Through_the_Action_of_Worms https://en.wikipedia.org/wiki/The_Formation_of_Vegetable_Mou...