Holy shit. Just look at that translucent little guy in the center, with its perfect little swirl. And the one at the bottom with its microscopic tiger stripes, never to be beheld except maybe by some unappreciative dick of a sand crab.
See, that's the thing about sand -- it's not just a bunch of tiny little rocks, it's a bunch of tiny little everything. In that picture, you're seeing little bits that have scraped off of the shells of sea creatures, some dried up plankton, coral, bits of minerals and who knows what else. Here's some sand from a lake in Minnesota:
And here's what you'll have stuck between your toes if you walked around a beach in Namibia (the pink and red stuff is garnet):
Via A Grain of Sand, Dr. Gary Greenberg
Sandcastles are much more desirable real estate than we expected.