Chapter fifteen of Snorri Sturluson's Gylfaginning, in Arthur Gilchrist Brodeur's translation, describes the world tree Yggdrasil and, among the beings that dwell around its roots, the serpent Nidhogg, who gnaws continually at the tree's lowest root from beneath. The passage locates Nidhogg within a wider ecology of hostile and monstrous creatures gathered at Yggdrasil, more than any man can imagine, and connects the tree's endurance to an ongoing, unresolved struggle rather than to any final, settled peace. Gylfaginning presents this gnawing not as a distant or symbolic detail but as a present, continuous fact of the cosmos as the text describes it standing at the time of telling, one of several threats the world tree survives moment to moment alongside deer that graze its branches and the eagle that perches at its top, with a squirrel named Ratatosk said to run up and down the trunk carrying insults between the eagle above and Nidhogg below. The chapter ties Nidhogg's activity to the tree's roots specifically, distinguishing this threat from the branches and crown, which face separate dangers described nearby in the same section of the Prose Edda, so Yggdrasil is shown under strain from more than one direction at once rather than from Nidhogg's gnawing alone.