The box appears to be copper.

The red lid is dented, one hinge shattered.

Inside waits a small quantity of the finest, driest powder, more brown than gray, more blue than green.

The greatest minds in creation make quick work of the material. The powder is weighed by the grain, and studied close, and remembered. One hundred billion bits of near-nothing reside inside the copper box, all of them tiny and nearly spherical, all etched with the outlines of continents and islands and icecaps. Each sphere represents a planet, and some of these tiny globes match known worlds.

There is one Earth and one Mars and a Venus too.

The box holds renderings of every habitable world in the galaxy.

One of them offers a simple explanation:

"The box is a message. The message is the minuscule nature of the box's cargo. It's the image of one hundred billion worlds barely filling two hands."

But if so, who is delivering this message? What vastness do they wish to impress on us? Is it a warning, or an invitation, or a taunt?