"clean" water and "waste" water in a sponge are all the same. Their bodies allow constant flow of water, there is no beginning and end to a sponge; thus technically waste water leaves a sponges body through its many pores.
When a sponge is submerged in water, the water enters the sponge through the tiny holes in the sponge. The sponge fills up with water, as a balloon fills with air, only not as visibly. When you...
Food enters the stomach where acids break down the material. In the small intestine, the material has much more fluid and the body begins to move that fluid to the kidneys as further break-down...