Speaking about the weird and wonderful patents applied for and granted from the late 19th century in an effort to create 'the perfect pipe' most are hidden from view (Masta, Youngs, Peterson, Lamberts Drybore etc.) and unless you disassemble the pipe and look inside the chamber and/or at the attachments to the tenon you wouldn't know the difference compared to a regular pipe.
The patents that are visible from the outside can seem extraordinary to us today and on some examples it's hard to know how the patent works and exactly what benefit it provides.
One of the most unusual I've come across is this unidentified
HOC Syphon patent 13397 made in Strasbourg ...
... of a type I've only seen once before on a clay pipe with removable bowl