One of them can be made when you cut it in half or in even smaller pieces. What will you do next? Take some baking soda and sprinkle a little on the two pieces of sponge. Then place these two (or more) pieces scattered in separate places in the refrigerator.
Let them act for a whole night or more. What will be the result? A refrigerator completely free of odors. This is because baking soda will have absorbed the smells and the next morning yesterday's smell of your fridge will be a thing of the past.
Try it and you will see the difference…