"Once my son came into the kitchen, opened a package of kitchen sponges, and played with them for a long time. And I had an idea. First, they are a universal construction toy. Thanks to a sponge’s rough surface, you can build anything with them. Second, you can imitate the washing of anything (we wash toy cars, our closets, and the floor) without damaging it. Third, they are really cheap. Fourth, they’re noiseless! And it’s also painless to step on them, and you can remove them when everyone’s asleep. Long story short, I’m surprised I didn’t have this idea earlier."