A torus is a three-dimensional shape that looks like a donut or a tube with a hole in the center. It is formed by revolving a circle in three-dimensional space about an axis that lies in the same plane as the circle. The resulting shape has two key properties: it is closed and continuous, with no edges or boundaries. The torus is a surface of revolution generated by revolving a circle in three-dimensional space one full revolution about an axis that is coplanar with the circle. The torus is a surface having genus one, and therefore possessing a single "hole". The torus shape can be found in various natural phenomena, from the pattern of magnetic fields around the Earth to the distribution of matter in galaxy clusters. It is also present in many biological structures, such as the shape of red blood cells, the arrangement of plant leaves around a stem, and the flow of air through the respiratory system. The torus shape can be found in various spiritual traditions, often representing the merging of the microcosm and macrocosm, or the individual and the divine. The torus has various types, including the ring torus, horn torus, spindle torus, and toroid. The torus is not a polyhedron as it has no flat faces. It is curved throughout, and it has a hole.