et al, Nuclear Potential Enrgy Surfaces and Critical Point Symmetry withen the Geometric Collective Model.
Z(5): Critical Point Symmetry for the Prolate to Oblate Nuclear Shape Phase Transition.
Point symmetry can produce some incredibly complex shapes, such as the Spirograph Nebula and the Cat's Eye Nebula.
As the stars orbit each other they can churn the winds in many different ways to create point symmetry.
A figure that has point symmetry
is unchanged in appearance after a 180 [degrees] rotation.
The X(5) critical point symmetry  has been found to correspond to the first order transition between U(5) and SU(3), while the E(5) critical point symmetry  has been found to correspond to the second order transition between U(5) and O(6).
Transition Probabilities in 154Gd: Evidence for X(5) Critical Point Symmetry.
B(E2) Values in 150Nd and the Critical Point Symmetry X(5).
Low Spin States in 162 Yb and The X(5) Critical Point Symmetry.
Low Spin States in 162Yb and The X(5) Critical Point Symmetry
The X(5) critical point symmetry  was developed to describe analytically the structure of nuclei at the critical point of the transition from vibrational U(5) to prolate axially symmetric SU(3) shapes.
Around N = 90 these seems to be the X(5)critical point symmetry.