Have you ever wondered where is the largest island in a lake on an island in a lake on an island? Now you know. (On earth, anyway.)
One interesting feature of this recursion is that it appears that deeper levels of recursion are most likely to be found in the same branches as shallower levels.
If we represent the "largest ___ in the" relation with "*", then the largest island in the largest lake in the largest island would be (island*lake*island). If (island*lake)^10 exists, is likely contained within (island*lake)^2. (Assuming larger lakes are more likely to have islands than smaller lakes.)
Of course man-made structures could quickly break the neatness of the recursion.
(HT: Reader JV.)