Why does cloth simulation not work on a NURBS sphere which has been converted to a mesh? I have created two spheres:


A UV sphere with 48 segments and 24 rings
A NURBS sphere, which I converted to a mesh using Object -> Apply -> Visual Geometry to Mesh


I then enabled cloth simulation, with the default options, to both meshes.  I placed a plane beneath them with collision enabled.

When I play the animation, only the UV sphere animates.  In fact, the converted NURBS sphere doesn't even fall, as shown in the image below.  Why is the cloth animation not working?



To clarify, although the spheres clearly have different geometry, it doesn't appear that the NURBS sphere has anything preventing it from deforming:



In addition, I can force some very strange behaviour if I place a cube with collision enabled intersecting the spheres.  The UV sphere simply pops up above the cube, while the converted NURBS sphere goes INSANE and explodes!



I would be very grateful to anyone who could explain this behaviour and how I can use a converted NURBS object with a cloth simulation.
Found the problem:

Select the converted nurbs object, press Tab to go in edit mode, press A to select all elements. Now press Alt+M and select By Distance.

This will remove all the unnecessary vertices, that essentially made the sphere a patchwork become one closed object with no split faces.

The reason Cloth did not work is that it needs a structure, the nurbs sphere was though only patches of separate faces.