Long ago, in our galaxy, on a temperate planet orbiting a modest star, a civilization arose. This was not the first civilization in our galaxy. Not by far. And ours was not the first galaxy to have a planet on which a civilization arose. Not by far. But this was the first of its kind in a way. Like many other civilizations, this civilization gave rise to more civilizations, and within a few thousand years the planet was thoroughly covered with civilized societies, large and small. Like many other civilizations, these civilizations waged terrible wars against each other, while struggling to maintain peace within themselves. Most civilizations in the universe, they come to a point where they realize they can kill off millions and destroy entire civilizations, and they begin to choose peace over warfare. Most civilizations in the universe, they come to a point where they realize they can kill off the entire planet, and they double down on peace, and do their best to eschew warfare. Not on this one planet. Somehow—and we don’t know what exactly happened, because all we have now are very scant archeological remnants—the civilizations on this planet chose to wage a war to end all wars, and they succeeded, by destroying not only all of the civilizations, but also most of the advanced life forms on the planet, through irradiation, climate change, and geological instability, which repeatedly churned up more and more radioactive isotopes from deep in the planet’s mantle.
Some advanced life forms did survive this catastrophe, including handfuls of the species that had destroyed the planet, in fortuitous shelters here and there. But, not for long. Advanced life forms need some degree of stability and/or regularity in their environments to survive. This planet could not provide that anymore, except in very small pockets for short periods of time. Radiation also made it difficult to pass on useful genetic innovations to the next generation. Most of the advanced life forms went extinct entirely. A few did survive, by devolving into single-celled organisms, when their circulatory cells found pockets of favorable conditions in which they could survive and reproduce.
One of these single-celled descendants—possibly of the formerly-civilized species—happened to mutate a gene that synthesized a silicon-boron compound that could protect the cells from radiation. This increased their chance of survival greatly, and other genetic innovations followed, such as the ability to harvest energy from electromagnetic radiation, and the organization of the compound into geometric shapes in which a small colony of cells could survive sudden changes in their environment, including complete desiccation, vacuum, and high heat. The most successful of these cells had a sixty-vertex shell, about 2 centimeters in diameter. Being descendants of intelligent species, these colonies developed the ability to move their shells in a rolling motion, and the ability to detect and move toward favorable conditions for reproduction. When such conditions were found, the shell would burst, releasing the individual cells of the colony, each of which had to very quickly and efficiently form a colony of its own, before the favorable condition dissipated again. Once the geology of the planet stabilized, these colonies were able to proliferate.
Over millions of years, these polyhedronoids came to cover the entire planet. Because all the essential ingredients of life they encountered became encapsulated in the shells, the planet’s crust was slowly depleted of these elements. Every time a few liters of organic matter chanced to pool somewhere, the polyhedronoids would descend upon the pool and almost instantly devour it, before any other life form had the time to give it a go. Eventually, there was no life left on this planet but the polyhedronoids, encapsulated in their shells, waiting for the next favorable condition, which would never again form on this planet.
As the star which the planet orbited, over a billion years or so, began to overheat, the planet lost its atmosphere, and the geological upheavals began anew. Being light for their size due to dessication, the dormant polyhedronoids were churned up off the planet’s surface, and carried into space by stallar winds, scattering throughout our galaxy. Billions upon trillions of them were released, and they traveled at incredible speeds across space. A few of them here and there found a planet on which there was a favorable condition, and there they did what they had done in their home planet, sucking up all ingredients of life in very short order. Even planets with advanced civilizations, like ours, were powerless against these mindlessly efficient, voracious invaders. After a couple of billion years, there was not a single planet left in our galaxy that could support life.
Now quadrillions and quintillions of these polyhedronoids are leaving our galaxy, and heading to others. We fear that they have acquired the ability to steer themselves in space, and some—a few trillion—are heading for your galaxy.
The planets on the edge of your galaxy that faces our galaxy, like your planet, of course, will be the first to meet these unwelcome guests. And your planet’s condition is very much favorable for the polyhedronoids.
Your only recourse is to destroy your planet before the polyhedronoids arrive. That is the only way you can help save life on your galaxy, although, we fear, this will only delay the inevitable.
We wish you luck.