This time, I'll bring the octagonal stamps to you.
Octagonal stamps, have 8 sides.
So far, all odd stamps are relatively new (from the 70's of the 20th century till now).
The following stamps however are dated 1898 !
Turkey was occupying Thessaly (now Greece) from 1897 till June 1898.
At that time, the following octagonal stamps were in use.
As you see, odd stamps aren't 'new', as these stamps show.
And there are many more ...