If you are reading this, your world is in grave danger. Touch nothing. Take no samples. Leave this place immediately. Destroy everything you have brought here, and never return. We have left this message in stone, in every language we have ever known, to stop a horrible threat. Heed these words, even though you do not want to.
“What does it say?”
“Beats me.”
“Isn’t language supposed to be a big subject for a linguistics specialist?”
“These are alien languages, meathead. They’re going to take years to figure out.”
“Languages plural?”
“From the patterns in the glyphs, it looks like it’s the same message repeated multiple times in different forms. It’s like some kind of Rosetta stone, but much bigger.”
“Yeah, these monuments are huge. They sure made a lot of copies.”
“Dozens at least.”
If you are reading this, you have missed, ignored or misunderstood the messages we launched in probes across the galaxy, and the one we transmitted from a beacon here for as long as the equipment lasted. You are careless in your haste to explore, as were we. This is your final warning. Heed these words, or you will suffer our fate.
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“Could it be a religious text?”
“Maybe. Building this structure and carving these tablets certainly took a lot of effort. They also put it at the nexus of all those road-like structures we saw from orbit. Whatever this says, I think it was pretty important to them.”
If you are reading this, you wonder how these ruins came to be, in a place of such abundance. You want to know why. Read our story, then turn back. Heed these words, or your curiosity will be your undoing.
“Well, upload your scans to the ship and we can beam them back home to see if anyone else can decipher it. Then come outside, we found something amazing.”
“What?”
“Just come outside, you’ve got to see this.”
We were like you. Our explorers once stood on another world, among the long-abandoned ruins of an alien civilization. They saw a message like this, but did not pause long enough to understand it. They became distracted by something they found more interesting. Heed these words, and do not make the same mistake.
“You pulled me away from the first alien languages ever discovered to show me … a fungus?”
“The closest analogue would be a lichen, or maybe a moss, but its genome isn’t like anything we know.”
“Fine, so it’s a lichen. What’s the big deal?”
“Look at this metabolic profile.”
“Mmm hmm. What am I looking at, exactly?”
“It’s photosynthetic, so it’s pumping out lots of oxygen, but it’s also carrying out the Sabatier reaction at ambient temperatures, fixing its own nitrogen, accumulating elemental sulfur and phosphorus from the rocks, and growing like a weed everywhere. Oh, and it seems to have its own radiation shield.”
“That’s one tough lichen.”
“It’s a one-species terraforming machine is what it is. Drop some of this on an uninhabitable space rock, and in a few decades it’ll be a paradise.”
On that distant world, we found a life form. It offered us a power we needed. We brought it from the other world, and it thrived here, just as it must have done for those who had found it before us. It grows now outside this building. We do not know how many other worlds it has reached. Heed these words, and do not let it reach yours.