I have a sphere and I want to make some cylindrical cavities on it's surface, which are tangent to the sphere's surface The cylinders wich which I should make the boolean difference should be disposed as a sea urchin, i suppose: with the bottom faces of the cylinders being on the same origin and the top faces spreading out radially.
Here are some images to give a better idea of what I should do:
This is a "flattened" version of what I want to acieve

How do I do the same thing on a sphere?
I need to get to the point where i get something like this but with the cylinders going all around the sphere orbiting around its Z-axis

Thanks in advance :D
Edit: Is there a versatile way of doing so on objects which have an elliptical/irregular shape?
What if the sphere were "squashed" on one axis and I wanted the cylinders to rotate around that axis (therefore performing an elliptical revolution)?
– torels Apr 26 '15 at 14:38