The dragon does not stop. That is the point. Níðhöggr gnaws the root of the world-tree at Hvergelmir, has gnawed since before memory, will gnaw until Ragnarök — and the tree stands. This is not despite the gnawing. It is because of it. In the adult human skeleton, approximately ten million resorption events are active at any moment. Osteoclasts — large multinucleate cells, six to twelve nuclei each — attach to the trabecular surface, secrete hydrochloric acid, activate cathepsin K, and dissolve a small cavity into the lattice. A Howship's lacuna: the physical signature of a completed osteoclast event, a small hollow in the surface of the strut. The dragon has been here. The osteoblasts follow and fill it. Ten percent of the adult skeleton is replaced per year. The skeleton you are carrying is not the one you had at thirty. The material has turned over. What has not changed is the architecture — the branching lattice of struts and plates, the geometry of load-bearing, the arrangement that knows where to be dense and where to be sparse. The form persists. The matter is continuously consumed. When the coupling breaks — osteoclast activity continuing while osteoblast response diminishes — the lacunae are not filled. The struts thin. The plates perforate. The branching lattice disconnects, strut by strut, each event unremarkable, until the architecture fails structurally. The world-tree does not fall to the dragon. It falls to the absence of the Norns. Níðhöggr was never the threat. The gnawing was always the condition.