Petros drew to a halt and crouched down beside it, smoothing the sand out of the way with his right hand. What he revealed was a length of pipe, although made of an odd substance he had never seen before. Corrugated and dark grey, the pipe was flexible in his hand. It deformed as he picked it up, partly moulding to the pressure exerted by his hand, and then reformed as he released it. It bounced slightly as it struck the ground. It was clearly empty -- all he could feel inside was air, and no full pipe would bounce like that.
He got back to his feet, ready to leave this mystery behind, and his eye fell upon the oasis pool. Or what had been the pool. It was nothing but wet sand, slowly drying in the night. Frowning, Petros bent and picked up the pipe again, this time keeping it in his hands and playing it out as he walked, following its path. It led to the pool -- what had been the pool. So, clearly, he concluded, it was meant to drain the water. But where did it go?
He tugged on the pipe experimentally, trying to see if it would pull free, to no avail. And he couldn't see where it went into the desert, given that the billowing sands had covered it completely past about three metres away from the oasis.
Petros frowned again. He wasn't sure what to do with this. He could see that the pipe was meant, somehow, to pull water from the oasis. The exact mechanism wasn't obvious, but there had to be a pump or similar somewhere, possibly buried in the desert, possibly some distance away. However, he had never seen a pipe quite like this. And, to his knowledge, this particular oasis was fed by an underground source -- far enough underground that digging to it had never made sense, but close enough to be detected with the few functioning glasses that remained. How could an underground river be drained so dry that the pool became empty?
And, moreover, what would be the point? Of course, tapping the river would make sense -- his people had thought of that one -- and whoever had put this pipe here clearly had greater technological resources available. But draining the river was another matter. It made the pipe useless, for one thing, and would force whoever had left it there to find another river to tap into.
He thought he was faced with a dilemma. Keep going as he had been, towards the cliff and Cene and the others, to try to discern their purpose. Or follow this pipe, and see if he could find who had left it here, and why they had done so. He clearly couldn't do both, and yet each had attractions to him.
And then he had a revelation. He started to follow the pipe away from the oasis, pulling it out of the sands as he walked. He had walked about six metres before he was sure. But by then he could tell: the pipe turned away from the oasis and headed almost straight north. Towards the cliff.
Petros dropped the pipe. And he started to run in earnest.