We didn’t know what had happened to the Pre–Corporation Rim colony that was on this planet long before Adamantine arrived. We just knew that at some point the Pre-CR group had encountered alien contamination, that it had been severe enough to result in "compulsive construction" of a structure over their original mostly underground habita tion, and that nobody was here when Adamantine arrived however many years later to start terraforming. The fact that the Pre-CR group had left equipment, including an active central system, behind in that original habitation, indicated that they had left in what Arada had euphemistically described as "disarray." If they had left, if they hadn’t all died or killed each other, their remains weathered to dust.