“Look! It’s the same shape as the damage above.”
The mat around the wound glowed brightly with pale phosphorescence.
“They made the same pattern each place?” Marc asked. “Some kind of experiment Chen was trying?”
“Beats me.” It seemed to be changing as she watched. “Look at it out of the corner of your eye,” she said. “See?”
“It’s spreading downward.”
She leaned over and peered around. “The glow increases below.” They looked down the vent.
Marc said, “It’s definitely brighter down there.”
“Let’s go.” They descended carefully, playing out line. Their lamps washed the mats in glare that seemed harsh now. Twenty meters down she said, “Lamps off again,” as they rested on a shelf.
When her dark vision came back her eyes were drawn to a splotch of light. “Damn! How—?”
“It’s the same shape again.”
“Right.”
Marc asked, “What the hell?”
“A mimicking image.”
“Naw, can’t be…”
“Parrots imitate sounds, this mat imitates patterns imposed on it, even destructive ones. But why?”
He drawled, “I’d say the question is, how the hell?”
“The mat here learned about the wound above.”
In the blackness Marc’s voice was baffled. “Learned?”
“Echoed, at least. Maybe automatically.”
“Okay, they’re connected. But why the same shape?”
She wondered herself, and guessed, “It’s a biological pictograph. I have no idea why. But I am sure that any capability has to have some adaptive function.”
“You mean it has to help these mats survive.”
“Right.”
On with the lamps and they dropped again. This tube was very nearly vertical, which made their descent quick. Still, time was narrowing. Julia felt incredulous, wondered if she was imagining the similarity in the damage patterns. But no: the image repeated on successively lower mats twice more, five meters apart.
Off with the lamps again. She gazed back up. The blurred gleaming above had faded. So it was not just a simple copying, for some pointless end. “The pattern, it’s following us down.”
Alarm filled Marc’s voice. “Tracking us?”
“See for yourself, up there—the image is nearly gone, and the one next to us is brightening.”
“Are you implying it knows we’re here?”
“It seems to sense what level we’re on, at least.”
“The one here is stronger than the others.”
“I think so too. Brighter the deeper we go. The glow is purely chemical, some signaling response I would guess. Maybe the denser vapor here deep in the vent helps it develop.”
“Signaling?” Marc sounded worried.
“Maybe just mimicking. Light would be the only way to communicate downward here. It couldn’t use chemical means to signal downward, the updrafts of vapor would blow them away. Sound could go either up or down, but it doesn’t carry well in this thin an atmosphere.”
His voice was strained in the blackness. “There’s got to be a simple explanation.”
“There is, but it doesn’t imply a simple organism.”
“Maybe it’s…signaling something else…”
“And if it’s brighter the deeper we get, maybe that means…something below?”
“The Airbus cable, it’s still slack.” He kicked it and waves propagated both up and down. At the next ledge down the lesion image began to swell into a strong, clearer version.
Something beyond comprehension was happening here and she could only struggle with clumsy speculations as she worked. Somehow the mat could send signals within itself. There were many diaphanous flags and rock-hugging forms, getting thicker, most of them pasty-colored. Somehow they all fit together, a community. They used the warmth and watery wealth here and could send signals over great distances, tens of meters, far larger than any single mat.
Why? To sense the coming pulse of vapor and make ready? A clear survival value in that, she supposed. Could organisms evolve such detailed response in this harsh place? Could a biofilm do it? On Earth they were considered to be early, primitive forms with severe limitations. Or had biofilms just been outrun by other forms in the rich, warm, wet oceans?
