Suspended

I went to a friend's house to pick up some prune plums - several pounds of them!  They're delicious.  I made a plum clafoutis that looks and smells so good.  We'll try dehydrating some.
Also went to town to pick up a couple of things and saw this jar lid suspended in a net hanging off a small stand that must be open on Saturdays at the market.  No idea of its purpose.  If I'm at the market and the stand is open, I'll investigate!  I'm wondering if something is put in the lid to attract wasps.