‘That’s a cache, isn’t it?’ remarked Corso.

‘It is,’ Whitecloud agreed. ‘The one at Tierra, to be precise. I only got a chance to take a look at this for the first time the other night. The main reason I didn’t get round to filing your report was because I wanted to check more of the correspondences before discussing it with you. But since you’re here . . .’

Whitecloud reached up towards the floating cylinder and nudged it to one side with an expert flick of his fingers, then he quickly navigated through another menu. A second cylinder appeared, similar to the first except that, rather than having a single primary shaft, this one had two shafts that merged in the middle, forming a cross.

Corso started. ‘That’s . . .’

‘The interior of the asteroid where we found the Mos Hadroch,’ Whitecloud finished for him.

‘But they look identical!’ Corso exclaimed, coming forward and putting both hands on the rim of the imager’s flat plate. ‘Well, no, not identical, but . . .’

‘But strikingly similar, wouldn’t you say?’

‘Yes.’ Corso nodded. ‘And you only just picked up on this?’

‘You’ll recall I was working outside on the hull during the briefing about the cache we just visited. A summary was forwarded to me, but I didn’t get round to studying it until now. Still, I don’t know how I missed it before,’ he admitted, a touch of wonder in his voice. ‘When I saw this for the first time yesterday, I was thunderstruck. The relationship was immediately obvious. Anyone with enough knowledge of the Atn could have made the connection, but there are so few of us left, really, and with the chaos of the last few years . . .’

Corso studied the two images and felt a chill that had nothing to do with the ambient temperature of the lab. ‘Just to be clear, you’re saying there’s obviously some kind of relationship between the Atn and the machine-swarm that created the caches?’

‘You sound surprised, but think about it for a moment. They’re both widely distributed, self-reproducing machine species. It’s certainly not beyond the bounds of possibility that they share some common point of origin. Perhaps what we’re seeing here is a case of some kind of genuine machine evolution.’ Whitecloud paused to think for a moment. ‘Or more likely one was created from the other.’

‘And the swarm was hunting down and destroying Atn clades.’ Corso, too, thought for a moment. ‘Can knowing this help us in any way?’

‘I don’t know,’ Whitecloud admitted. ‘Just about the first thing I did, once I realized this, was to try and crack the Mos Hadroch with the Atn’s own machine-protocols. I got nowhere, though that’s not to say there aren’t other commonalities between the species that might give us the key we need to understanding how the artefact actually works.’