Clean and sanitize that sponge and microwave. Don't be grossed out by my microwave but this is how it gets after a couple of weeks of use. No one thinks to cover anything up in the house. I digress.
Okay so we all should be sanitizing our kitchen sponges. A great way to do that and to clean your microwave is to take your sponge and get it good and wet. Put a big squirt of dish soap on it and toss into the microwave. I then run the microwave for 90 seconds.
The sponge gets good and hot and the steam helps to loosen the food stuck on the microwave. Then take the sponge once it cools a bit and wipe down the microwave. You have killed the germs in the sponge with the heat and cleaned up the microwave in short order.