Alexander horned sphere

The Alexander horned sphere is a classic example in topology, specifically in the study of knot theory and manifold theory. It is constructed by taking a sphere and creating a complex embedding that demonstrates non-standard behavior in three-dimensional space. The construction of the Alexander horned sphere involves a series of increasingly complicated iterations that result in a space that is homeomorphic to the standard 2-sphere but is not nicely embedded in three-dimensional Euclidean space.