Dr. Hu Noah and most of his students were Ivyn. In Doc’s case it was difficult to tell, since extreme old age tended to obscure racial differences. He’d lost his hair long ago, and his skin was blotchy from years spent down on the surface doing research in unfiltered sunlight. Limp skin dangled from his sharp cheekbones like wet laundry from the edge of a rock, and eventually joined into a system of wattles mostly concealed by a scarf wrapped around his neck. That, and other touches meant to keep him comfortable, had been seen to by his nurse, a stocky Camite wearing a knapsack full of medical supplies. Curled at Doc’s feet like a sleeping dog was a grabb with a display panel in its back showing live readouts of his vital signs, which it was monitoring through a bundle of wireless connections. A pole projected vertically from its back to about the level of Doc’s waist, where it forked to a pair of handlebars. It was a smart cane. When he grabbed the handlebars it would help him stand up. It would then steady his locomotion even on the roughest terrain, adding its six legs to his two.