When you take a moonlit stroll on the beach, how often do you think about the tiny grains of sand creeping in between your toes? From above, sand seems like a bunch of tiny brown rocks, perhaps peppered with occasional shells or cigarette butts. But sand has a far more fascinating story to tell.

Composed of the remnants of volcanic explosions, eroded mountains, dead organisms, and even degraded man-made structures, sand can reveal the history—both biological and geologic—of a local environment. And examined closely enough, as the scientist and artist Gary Greenberg has, sand can reveal spectacular colors, shapes, and textures.
These images of sand from around the world were taken by Greenberg using an Edge 3D Microscope and can be found in his book, A Grain of Sand, which was published earlier this year by Voyageur Press.

Not all sand is made of tiny bits of rock. Biogenic sand, which forms from the remains of marine life, is the major ingredient of many tropical beaches. The grains here are tiny fragments of a baby sea urchin shell.

The raised bumps on the white grain represent the sites of insertion for the sea urchin’s spines. The blue grain has eroded to the point that the raised bumps have been completely rubbed off. (Magnification 100x)

Looking like a puffy white star studded with little pearls, this is the shell of an amoeboid protist called a foraminifera, or foram. An estimated four thousand types of forams live in the world’s oceans.

The shells, called tests, are made mainly of calcium carbonate, which the animals derive from carbon atoms in the air and water. Forams thus play a significant role in the carbon cycle. (Magnification 75x)
 

（Original from：http://discovermagazine.com/photos/01-each-grain-of-sand-a-tiny-work-of-art）