Remember I asked about those quadrant shaped flat pieces of stone in the corners of the Custom's House Exterior?
Rory I think sugested they were to stop people urinating in corners[the stones slope down toward the trousers]. That seems like a good theory to me.
We were in Venice again last week and my girlfiriend and I spotted a HUGE one not far from Corso Nuovo. It's about 4 feet in radius! and almost touching the ground. Very steep angle. I don't know - my girlfriend suggested it's a structural support.
Unless it's for stopping elephants...
Who knows how some of these features come about. I presume lots of them start in a mundane fashion and then become encorporated into newer deigns when the original purpose is forgotten. Sometimes becoming decorative in themselves.