The hog tusk, after the root had been sawed off to form a base, still stood as tall as the lampwright, and was more than twice as wide as she was. Carving the spiral into it was a work of weeks. The spiral path had to wind up, and down again, without crossing, or meeting meeting itself. It had to be recessed deeply into the ivory, but without creating any holes, and the back wall bent just so.
After the future lamp was the right shape, it needed the right surface. The lampwright's long fingers made polishing the recesses with silt and clay easier than it would have been for some others. It still was slow work, needing near endless patience.
Once she was satisfied with her work, its smooth curves cleaming in the lantern light, she met the stablemaster to pick out its occupants.
There was a batch of the local glow worms, with their orange-yellow light and warm brown carapaces. The lampwright and the stablemaster brought selected animals new lamp in separate baskets, and added them one by one, alternating male and female. The lampwright sighed in relief and satisfaction when she saw she had judged the length of the path correctly. Each could see the light of the glow worm in front, and followed it. The slow procession lit the underground hall, more safely than air-eating fire. The lanterns could be extinguished, or put to use elsewhere.