The monster came from a swarm of stars that humans call Messier 22, a globular cluster ten thousand light-years distant. A million stars with ten million planets—all but one of them devoid of significant life.
It’s not a part of space where life could flourish. All of those planets are in unstable orbits, the stars swinging so close to one another that they steal planets, or pass them around, or eat them.
This makes for ferocious geological and climatic changes; most of the planets are sterile billiard balls or massive Jovian gasbags. But on the one world where life has managed a toehold, that life is tough.
And adaptable. What kind of organisms can live on a world as hot as Mercury, which then is suddenly as distant from its sun as Pluto within the course of a few years?
Most of that life survives by simplicity—lying dormant until the proper conditions return. The dominant form of life, though, thrives on change. It’s a creature that can force its own evolution— not by natural selection, but by unnatural mutation, changing itself as conditions vary. It becomes whatever it needs to be—and after millions of swifter and swifter changes, it becomes something that can never die.
The price of eternal life had been a life with no meaning beyond simple existence. With its planet swinging wildly through the cluster, the creatures’ days were spent crawling through deserts gnawing on rocks, scrabbling across ice, or diving into muck—in search of any food that couldn’t get away.
The world spun this way and that, until random forces finally tossed it to the edge of the cluster, away from the constant glare of a million suns—into a stable orbit: a world that was only half day and half night; a world where clement seas welcomed diversity. Dozens of species became millions, and animals crawled up from the warm sea onto land grown green, buzzing with life.
The immortal creatures relaxed, life suddenly easy. They looked up at night, and saw stars.
They developed curiosity, then philosophy, and then science. During the day, they would squint into a sky with a thousand sparks of sun. In the night’s dark, across an ocean of space, the cool billowing oval of our Milky Way Galaxy beckoned.
Some of them built vessels, and hurled themselves into the night. It would be a voyage of a million years, but they’d lived longer than that, and had patience.
A million years before man is born and its story begins, one such vessel splashes into the Pacific Ocean. It goes deep, following an instinct to hide. The creature that it carried to Earth emerges, assesses the situation, and becomes something appropriate for survival.
For a long time it lives on the dark bottom, under miles of water, large and invincible, studying its situation. Eventually, it abandons its anaerobic hugeness and takes the form of a great white shark, the top of the food chain, and goes exploring, while most of its essence stays safe inside the vessel.
For a long time, it remembers where the vessel is, and remembers where it came from, and why. As centuries go by, though, it remembers less. After dozens of millennia, it simply lives, and observes, and changes.
It encounters humanity and notes their acquired superiority— their placement, however temporary, at the top of every food chain. It becomes a killer whale, and then a porpoise, and then a swimmer, and wades ashore naked and ignorant.
But eager to learn.