image credit: Bjornar Sandnes, University of Oslo; image source; larger image
Is this the maze from Labryinth or the back of a kid's cereal box? It's actually fingers of air winding through a fluid and grain mixture as it drains. You can see more pictures here.
Find out about granular materials and research going on in the field from this University of California, Santa Barbara research page.
The Physics of Sandcastles
Here's a practical application for the physics of sand--learn how you can make the ultimate sandcastle at Sandcastle Physics Revealed and The Physics of Sandcastles.