We report the observation of controlled expansion of a two-dimensional quantum gas confined on a curved shell-shaped surface. Starting from the ellipsoidal geometry of the dressed quadrupole trap, we introduce a new gravitational compensation mechanism that can explore the full ellipsoid. The zero-point energy of lateral confinement is manifested by the spontaneous occurrence of annular shapes in atomic distributions. The experimental results are compared with the solution of the Gross-Pitaevskii equation in 3D and the semi-analytical model in 2D. This work demonstrates how hidden dimensions can dramatically affect embedded low-dimensional systems by inducing topology changes.
