“Not surprising, though, after what he went through,” Rob said. “He must have been in terrible condition when they finally picked him up.”

“Not as bad as you’d think. Once he got past perihelion, he did everything right. The old logs of that trip are still in his office. They make interesting listening — I’ve played them myself. Regulo had the sense to ignore everything about the Alberich until he had treated his burns and doped himself up to sleep for a solid twenty-four hours. That took real nerve, to put himself under for so long when the Sun was still big and blazing and he didn’t know if he’d be picked up at all.”

“But why couldn’t they do anything about his face?” Rob asked. “I mean, no matter what the burns were like, surely they could have used grafts or regeneration to repair most of it. I’ve never seen scars like that, and I’ve had bad accidents to my crew on construction jobs.”

Corrie did not answer. She stared straight ahead with a curious expression on her face, as they left the craft and began to walk together to the entry point of Way Down. Rob waited for a reply. When it did not come, he turned to her and looked more closely. Corrie’s skin had paled, so that the smooth tan had become like old ivory, cold and bloodless.

“Are you feeling all right?” he asked. “It never occurred to me to ask before, but I hope you’re not claustrophobic.”

She shivered and forced a smile. “Just a little bit. I’m all right, though. I know what it will be like at Way Down, and it won’t worry me. Come on, let’s start down.”

She walked quickly ahead of Rob, to where the four great elevators stood in the center of the Way Down entrance facility. She stopped at the first elevator, the fast express that would descend twelve miles in less than two minutes, flashing smoothly through the evacuated shaft.

“No. Not that one.” Rob came up beside her and took her arm as she was about to press the Call key. “That’s the nonstop. We want one that we can stop partway down. It’s the one at the end of the building, past the heavy-load elevators.”

“Partway? There’s nothing to stop for,” protested Corrie; but she allowed herself to be led along the broad corridor to a smaller elevator and watched in silence as Rob manipulated the depth selector. He set it to halt a little more than a mile and a half down.

“Just wait and see,” he said. His look was self-satisfied and expectant. “There are things about Way Down that the average customer never knows. Anyone can use this elevator, but most people have no reason to want to. Ready?”

Corrie nodded. The descent began, with the car supported and accelerated by linear synchronous motors set at regular intervals along the length of the shaft. As Rob adjusted the polarization of the surrounding field the walls of the car became transparent. He dimmed the internal lights and switched on an external illuminator set above the ceiling of the car. The sides of the shaft became visible, flashing past them. As they moved deeper Rob gradually slowed the descent. They moved steadily past multi-colored rock strata: hematite reds and silvers, the deep blue of azurite, slate-grays and dark emerald green. The rock layers drifted by them as they fell, slower and slower. The car stopped at last alongside a thick seam of shining black rock. It formed a continuous wall, except at one point where a circular opening about three feet across had been neatly cut.

“This is it,” Rob said. He glanced at his watch and nodded. “Any time now. Take a look through the opening, and keep watching along that corridor.”

The circular window looked out onto a horizontal shaft about four feet high, leading away into the depths of the black rock. The lights from the car cast their reflection just a few yards along the dark tunnel. Corrie, her skin prickling with anticipation, stared out into the darkness. Suddenly she saw a faint movement at the limit of visibility, deep in the corridor. She strained to see it more clearly. A dark shape was moving out of a side shaft to the main tunnel. The form was long and flat, a little more than three feet tall. She could see a blind, stubby head, and as her eyes adjusted to the dim light she could gain an idea of its size. The body appeared to be endless, approaching them silently on broad, black feet. It came closer and closer, shuffling along the tunnel. Finally she could see the whole beast. It was supported on eight pairs of short legs, and formed a long, black-furred cylinder. The rear end of the animal had not one tail but five, long sinewy tentacles. Each lifted above the broad back and ended in a ringed orifice. Corrie judged the whole creature to be about ten meters long. As it continued to come closer, she stepped back from the window.

“Don’t worry,” said Rob. “It’s harmless. Keep looking.”

Corrie turned to him in sudden comprehension. “I know what it is! It must be a Coal Mole.”

“Quite right.” Rob was grinning in triumph. “I told you you’d have something to see down here. When I called from the ship I wanted to check whether there would be one of them anywhere near the Way Down shaft. When I found that there was, I called Chernick and asked if he would direct it here at the right time for us to take a look.”

Corrie was staring at the Coal Mole in fascination. “I’ve never seen anything like it in my whole life.”

“I believe you. Very few people have.”

“But what does it live on? I know Chernick says that he breeds them, but I thought that was just a funny way of describing their manufacture. It looks like a real animal, but surely it can’t be?”

Rob shrugged. “If you’ll define a real animal, I might be able to tell you if it is one. The Coal Moles feed, they move, they reproduce, but they can’t function without Chernick’s microcircuitry inside them. They couldn’t exist in Nature without the inorganic components that humans have added — but lots of pets couldn’t survive in the wild, either.”

“How does it mine the coal?” asked Corrie. The Mole, having come within a couple of meters of the window, was now backing silently away again down the tunnel.

Rob nodded his head at the receding creature. “See the rear end there? Those tentacles handle the narrow seams. One of them can chew along a layer that’s only a few centimeters thick. The head end handles the big seams. As you’d expect, the teeth regenerate continuously — it’s tough work, crunching up coal, but I suppose it’s not much different from a beaver, chewing through wood. The Mole stores the ground-up coal in the main body pouch, and when it’s full it takes it back to a central storage area and dumps it.”

“And it eats, like an ordinary animal? What does it feed on?”

“Mostly coal — what would you expect? It takes about one percent of what it mines to drive its own metabolism, so it’s very efficient. It’s a bit like a bee, eating some of the nectar and taking most of it back to the hive. The only other thing it needs is water, and there’s a supply of that at the storage areas.” Rob put his hands to the controls. “Ready to descend the rest of the way? There’s nothing more to see here, or until we get to Way Down.”

Corrie nodded, but she was still gazing along the tunnel where the Mole had disappeared into the darkness. “Won’t it be coming back to mine?”

“Not here. They don’t mine coal this close to the Way Down shafts. I asked Chernick to send it towards us, just so we could see it. He grumbled a bit — said it wasn’t kind to the Mole, it’s not happy if you take it away from its job. It’s on the way back to the seam now, a mile or two away. Chernick rotates the Moles among the different coal types, he says that for some reason they do better if they’re rotated. One week on anthracite, one on bituminous, one on lignite. I suppose they pick up different trace elements they need from different types of coal. I’ll have to ask him about it sometime — he almost thinks like a Coal Mole himself.”