gregeganSF, This is a finite piece of Dini’s surface, which has constant negative Gaussian curvature. The same shape, extended indefinitely, can embed an infinitely long strip of the hyperbolic plane, with a geodesic G as one boundary and a hypercycle (a curve a fixed distance from G) as the other. The geodesic is mapped to the central axis of Dini’s surface, while the hypercycle is mapped to the outer helix.
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