Humans may know a lot about the world, but there are still many questions that remain unanswered. What do the tops of the pyramids in Egypt look like? Can the Sahara Desert turn into a lush, green forest? Can an avocado kill a horse? Why is penguin poop necessary for survival?

National Geographic has provided answers to your most burning questions. You can’t even imagine some of the things you don’t know about the world! Learn more about your ad choices. Visit megaphone.fm/adchoices