This is a fruit fly trap, reminiscent of the iconic Sydney Opera House.
It screws on as a lid on standard 50 mm diameter glass jars. Taco sauce, jam and Dijon mustard are products commonly sold in this smaller jar size.
I fill mine with a mixture of water, a drop of dish soap, some wine vinegar and sugar. Fill it quite high to give them little space for navigation once the flies enter inside. It's very effective.
The author marked this model as their own original creation.