Does the human body contain gold? Can eating spinach really make you stronger? Quench your curiosity with the fascinating facts behind every-day mysteries. Why do cats knead? Why do you have a fever when you get sick? Why do they say dogs have good noses? Why does your heart beat faster when you do sports? Why do horses sleep standing up? Why is seawater salty? Believe it or not: Our ears and nose keep growing our entire lives! Dolphins sleep with one eye open! Should you wake up a sleepwalker? Does eating spinach make you strong? Do bears sleep all winter? What do small animals eat in winter?