"So they ingested the gold as larvae..."
"Went into a cocoon..."
"And when they emerged, their bodies were encased in gold."
"And there they are," said Sel, holding up the light again. Only now he went closer to the columns, where they could now see that the glints of reflection were from the bodies of half-formed creatures, their backs embedded in the pillars, their foreheads and bellies shiny with a layer of thin gold.
"The columns are the cocoons," said Po.
"Organic mining," said Sel. "The formics bred these things specifically to extract gold."
"But what for? It's not like the formics used money. Gold is just a soft metal to them."
"A useful one. What's to say they didn't have bugs just like these, only bred to extract iron, platinum, aluminum, copper, whatever they wanted?"
"So they didn't need tools to mine."
"No, Po--these are the tools. And the refineries." Sel knelt down. "Let's see if we can get any kind of DNA sample from these."
"Dead all this time?"
"There's no way these are native to this planet. The formics brought them here. So they're native to the formic home world. Or bred from something native there."
"Not necessarily," said Po, "or other colonies would have found them long before now."
"It took us forty years, didn't it?"
"What if this is a hybrid?" asked Po. "So it exists only on this world?"
By now, Sel was sampling DNA and finding it far easier than he thought. "Po, there's no way this has been dead for forty years."
Then it twitched reflexively under his hand.
"Or twenty minutes," said Sel. "It still has reflexes. It isn't dead."
"Then it's dying," said Po. "It has no strength."
"Starving to death, I bet," said Sel. "Maybe it just finished its metamorphosis and was trying to get to the tunnel entrance and stopped here to die."
Po took the samples from him and stowed them in Sel's pack.
"So these gold bugs are still alive, forty years after the formics stopped bringing them food? How long is the metamorphosis?"
"Not forty years," said Sel. He stood up, then bent over again to look at the gold bug. "I think these cocooned-up bugs embedded in the columns are young. Fresh." He stood up and started striding deeper into the cavern.
There were more gold bugs now, many of them lying on the ground--but unlike the first one they found, many of these were destroyed, hollowed out. Nothing but the thick golden shells of their backs, with legs discarded as if they had been...
"Spat out," said Sel. "These were eaten."
"By what?"
"Larvae," said Sel. "Cannibalizing the adults because otherwise there's nothing to eat here. Each generation getting smaller--look how large this one is? Each one smaller because they only eat the bodies of the adults."
"And they're working their way back toward the door," said Po. "To get outside where the nutrients are."
"When the formics stopped coming..."
"Their shells are too heavy to make much progress," said Po. "So they get as far as they can, then the larvae feed on the corpse of the adult, then they crawl toward the light of the entrance as far as they can, cocoon up, and the next generation emerges, smaller than the last one."