A sponge is a cleaning aid made of soft, porous material. Typically used for cleaning impervious surfaces, sponges are especially good at absorbing water and water-based solutions.
The best way to clean a sponge and minimize germs is to wash the sponge daily in hot, soapy water and then microwave it wet for two minutes
Sponges are made of loose fibers with lots of space between them. The holes between the sponge fibers absorb the water, and so the sponge material swells up with water. This stops the water coming out of the sponge when you lift it out of the water