What if we didn t have mucus? The insides of our bodies would be very dry, and we would find it hard to digest our food. We would also quickly become sick, because mucus protects us from dirt in the air that we breathe. But what exactly is this sticky, slimy stuff we call mucus? What s it made of? Is it the same thing as snot? Why do we produce more of it when we have a cold? And what do animals like slugs and snails do with their mucus? You might find it a bit gross, but you wouldn t want to live without snot!