https://simple.wikipedia.org/wiki/Spiral
Three-dimensional spirals. For simple 3-d spirals, a third variable, h (height), is also a continuous, monotonic function of θ. For example, a conic helix may be defined as a spiral on a conic surface, with the distance to the apex an exponential function of θ.. The helix and vortex can be viewed as a kind of three-dimensional spiral.. For a helix with thickness, see spring (math).