Marbles, Music and Sand!
image from DepositPhotos
Marbles make beautiful music when working in this machine:
https://thekidshouldseethis.com/post/the-wintergatan-marble-machine-music-made-from-2000-marbles
image from Earth Eclipse
Sand becomes a liquid in this video:
https://thekidshouldseethis.com/post/royal-institution-fluid-sand-video
