"Hmm." Larionova closed her eyes and tried to picture it. Pockets of warm water, deep in the ice of Mercury; luxuriant mats of life surrounding mineral-rich hydrothermal vents, browsed by Dixon's mercuric animals... was it possible?

Dixon asked, "How long do the vents persist?"

"On Earth, in the Ridge, a couple of decades. Here we don't know."

"What happens when a vent dies?" Larionova asked. "That's the end of your pocket world, isn't it? The ice chamber would simply freeze up."

"Maybe," Scholes said. "But the vents would occur in rows, along the scarps. Maybe there are corridors of liquid water, within the ice, along which mercurics could migrate."

Larionova thought about that for a while.

"I don't believe it," she said.

"Why not?"

"I don't see how it's possible for life to have evolved here in the first place." In the primeval oceans of Earth, there had been complex chemicals, and electrical storms, and...

"Oh, I don't think that's a problem," Scholes said.

She looked at him sharply. Maddeningly, he was grinning again. "Well?" she snapped.

"Look," Scholes said with grating patience, "we've two anomalies on Mercury: the life-forms here at the South Pole, and Dolores Wu's artifact under Caloris. The simplest assumption is that the two anomalies are connected. Let's put the pieces together," he said. "Let's construct a hypothesis..."

Her mandibles ached as she crushed the gritty Ice, carving out her tunnel upwards. The rough walls of the tunnel scraped against her carapace, and she pushed Ice rubble down between her body and her carapace, sacrificing fragile cilia designed to extract soft food particles from warm streams.

The higher she climbed, the harder the Ice became. The Ice was now so cold she was beyond cold; she couldn't even feel the Ice fragments that scraped along her belly and flukes. And, she suspected, the tunnel behind her was no longer open but had refrozen, sealing her here, in this shifting cage, forever. The world she had left -- of caverns, and Chimneys, and children, and her Three-mates -- were remote bubbles of warmth, a distant dream. The only reality was the hard Ice in her mandibles, and the Seeker heavy and questing inside her.

She could feel her strength seeping out with the last of her warmth into the Ice's infinite extent. And yet still the Seeker wasn't satisfied; still she had to climb, on and up, into the endless darkness of the Ice.

...But now -- impossibly -- there was something above her, breaking through the Ice...

She cowered inside her Ice-prison.

Kevan Scholes said, "Five billion years ago -- when the Solar System was very young, and the crusts of Earth and other inner planets were still subject to bombardment from stray planetesimals -- a ship came here. An interstellar craft, maybe with FTL technology."

"Why? Where from?" Larionova asked.

"I don't know. How could I know that? But the ship must have been massive -- with the bulk of a planetesimal, or more. Certainly highly advanced, with a hull composed of Dolores' super dense Pauli construction material."