Ever wondered what all that junk in your DNA trunk is doing? Find out in  this QotW! Plus, we ask: what's the point of two sets of organs? Like this podcast? Please help us by <a href="https://www.thenakedscientists.com/donate">supporting the Naked Scientists</a>

Why do sandy footprints appear raised?

Each week we set out to solve one of the world's weirdest, wackiest, funniest and funkiest scientific puzzles. And along with the answer there's a brand new question to think about for next time...