It's a round black orb with numbers, and each number lives in a flattened area of the surface. They were flattened so that the user could roll it and it would land on a number, and the shaky substance inside helped it eventually stop.
But alas! One day tragedy struck! And somebody who was not me accidentally broke it in half! The northern hemisphere broke off from the southern hemisphere, which made me sad.
But now I could finally see what was inside. It was 39 tiny pebbles. They left a thin layer of silt on the inside surface of the orb, most likely a product of stones rubbing against each other, knocking off microscopic particles which stick to the soft plastic surface.
But wait, there's more!
The orb itself is made of two layers; a transparent outer layer covered with flat surfaces, and a smooth round inner layer covered with numbers.
Right near the north pole (marked by the number "100") are two holes. The presence of these two holes puzzled our researchers at first, until it was discovered that on the inside of the clear outer orb are two tabs which fit into the holes. The two layers of the southern hemisphere are stuck together by an unknown force or substance.
Here are all 42 parts of the orb with each other.
Here it is with the inner layer removed.
The die died, but in its death it helped further the pursuit of science. So it did not die in vain.