Which shape best models a universe with negative curvature ($\Omega_0 < 1$)?

Answer

A saddle shape

Negative curvature corresponds to an open universe, which is geometrically modeled by a saddle shape. In this geometry, parallel lines diverge and spread farther apart as they extend through space.

Which shape best models a universe with negative curvature ($\Omega_0 < 1$)?
NASAuniversecosmologyshape