Sand! We use it to make all kinds of things, from spectacular sandcastles to roads and bridges. But where does it come from? And why is the sand on so many beaches disappearing? In this episode, Molly and co-host Leon head to the beach to explore the secrets of sand. They run into the ultimate sand STAN Sanden Totten and discover what it's made of. Then, they chat with producer Nico Gonzalez Wisler about why beaches are running out of sand. All that, plus a stumper of a new mystery sound! Do you have your Smarty Pass yet?? Get yours today for just $4/month (or $36/year) and get bonus episodes every month, and ad-free versions of every episode of Brains On, Smash Boom Best, Moment of Um, and Forever Ago. Visit www.smartypass.org to get your Smarty Pass today! ____________ This episode was sponsored by: Sitka Seafood Market - Use promo code Molly35 to receive $35 off your first order.  Indeed - Use promo code brainson to receive a $75 sponsored job credit