Thank you Anne, I guess the title of this thread needs changing then as it is a bit misleading.

You could suspend something from the prongs or hold something in position in the centre of the jar, like several vanilla pods in a sugar pot (probably not a good example). There are also two areas on opposite sides of the pot which have tiny raised diamonds giving a rough texture, they provides a lot of grip if that is their purpose.
The more I think about it the more I believe the prongs are for holding something but I have no idea what.
John