Many thanks to plastikk for directing us to that collection.
I might not be the first to have noticed this, but in the pic below there is something protruding from the rear of the housing of the "horn" - maybe a tensioner for the idler?
There's also a rod of some kind joining the pair of horns on each track. perhaps the idea was to protect the track and idler from damage and abrasion if the vehicle were to come across a brick/stone building or even a pillbox. The horns would concentrate the pressure so as to punch a hole in an obstacle and save the track/sprocket from having to do it.
"Sometimes things that are not true are included in Wikipedia. While at first glance that may appear like a very great problem for Wikipedia, in reality is it not. In fact, it's a good thing." - Wikipedia.
That's an excellent photo, very clear. The rod joining each pair of horns is visible in other photos, even poor quality ones. It looks more robust close up than appears the case from further away, so I think it quite likely that it's some sort of protector device just as you say. A possibility that has just come to mind is that the horns and their crossbars were intended for felling trees when driving through woods. How aware the designers of the tank were of the lack of brick/concrete structures to ram is anyone's guess; buildings and trees do seem the likely reason though.
The 'bolt' sticking out of the housing does look like it will be the tensioner. Who knows, they might have decided on an external tensioner for simplicity (rather than the fancier recessed design on British tanks), then thought "hmmm, those stick out a lot, maybe we should stick something on the end so's they don't catch on things"?
