The sponge itself acts like skin would to a body, it functions as a squishy barrier to protect the innards. Both the sponge and the human skin are built to do the same thing. But, a vital difference is the layers that human skin has. Skin has multiple layers that all vary in thickness and utility. The sponge is only one layer, which in my opinion, could have been a downfall in the design. And through the lymphatic system, the integumentary system can repair wounds, whereas if the sponge is damaged, it will not be able to naturally repair. Here is where cushioning starts to play a big role. The muscular system is essentially a big cushion that also provides mobility. The sponge and muscles provide not only a soft cushion, but the popcorn provides stability for the egg, similar to the stability that muscles give to the inner body. The muscular system is also good at absorbing impacts, though not as extreme as the skeletal system. The sponge, though, does not move like muscles do. While it does provide all the benefits in terms of cushioning, it cannot provide the movement that the muscular system is primarily focused