Extruded sphere has loop with no normals - how to fix? I've extruded a sphere which I later deform with a shape-keyed lattice. All's well, except that when deformed, I see a discontinuity in the shading. Inspecting the face normals, I see the following:



You can see that there's a loop which has two odd characteristics:


It has both edge and face markers;
It has no normals (and they're not just pointing the other way, they really appear to be absent).


Selecting everything and recalculating the normals had no effect.

If I select an edge segment along that loop and delete the edge, one of the adjacent faces gets deleted too.

I think this is an edge from which I extruded to lengthen the tube.

How can I repair this loop?
I just created a similar object by extruding from a circle,dragging upwards then extruding and not dragging, then extruding a third time and dragging up.

The resulting ring of faces with no surface area I removed by selecting All then going to the Tools panel > Remove > Remove Doubles.