Add Yahoo as a preferred source to see more of our stories on Google. Your small intestine is lined with tiny protrusions called villi that play a big role in digestion. Sebastian Kaulitzki/Science ...

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to CuriousKidsUS@theconversation.com. How does your body make poop? Owen, 4, Wakefield ...