What 3d shape has one line of symmetry?

A 3D shape with one line of symmetry is a cone. The line of symmetry runs vertically down the center from the apex to the base, dividing the cone into two symmetrical halves. This symmetry is evident in the shape's circular base and tapering sides. Other examples include certain types of pyramids, like a square pyramid with a vertical line through the apex and the center of the base.