are you looking to make a true ellipsoid shell? If so you can still use the basic shape objects and a combination of SEO to create a shell. In the past this method was necessary.
With the new shell tool I believe you could create the arc path of the ellipsoid, complete a rotation around the x, y or z axis depending on whether you are looking for a prolate or oblate ellipsoid. If you are looking for a scalene ellipsoid you can perhaps modify the angle of the arc to get the desired distortion.
Then using SEO you could trim the lower portions of the ellipsoid to get the desired height.
I haven't tried any of this specifically, but I deal with shells every day and have found the new shell tool to be a great asset in my workflow, especially since SEOs now display properly in relation to shells and roofs.
Graham
Graham Whipple
Resin Architecture
Idaho USA