Cheese dome
When the OP posted this picture on Reddit, people were quick to offer a wide range of answers, from the ridiculous to the reasonable. Some said it was a lampshade, though we’ve never seen a lamp with a glass shade before. Another person said it was a cheese dome. Seriously, dude? A cheese dome?
As ridiculous as this sounds, this is the right answer. Cheese domes are domed-shaped objects that cover, well, cheese. If you don’t feel like popping your cheese in the fridge every time, perhaps you don’t want to eat cheese condensation (a.k.a. cheese sweat), then you can leave it on your kitchen countertop covered with a cheese dome.