Penny spurs or are they?
This is a 1926 Penny that shows a dieclash where the facial side of the obverse is clearly shown as indicated by the red arrows. What appears to be markings at the back of the head don't seem to line up.
In this image I have highlighted the rough outline of the facial features to make them stand out more easily.
I have overlaid and lightened the reverse side onto the obverse as a dieclash would occurr and the facial areas line up extremely well, making me consider that my hunch is correct.
Now to spurs
I have highlighted the area at the chin and neck. I put several of these "spurs" on the coin forums quite a few years ago and the consensus was they are spurs. I disagree and believe they are actually caused by dieclash. If you look at the shape of the highlighted area, it closely mimics the shape of these "spurs".
This 1924 example show the "spur" on the second N in PENNY, where they all seem to occurr, but also shows the outline of the facial features. This is a dieclash in my opinion. Some of the "spurs" show on the N but no facial features are apparent, and there are some multiples following.
Another view of the same coin which show the back of the head clearly and also the ear.
And some multiples
A triple "spur" which could only occur with die-clashes and die rotation during the time the die was used to strike the number of coins required. The third "spur" is less easy to see and is the lowest. I have a few GeorgeV coins showing some amount of rotation.
Close-up image of a 1921 example.