Sponges are a type of aquatic animal whose body is covered in tiny pores called ostia. The ostia allow water, oxygen, and other nutrients to flow into the sponge's body, and for waste products like ammonia and carbon dioxide to exit their body. The respiratory system of a sponge is based on the process of diffusion.
The shape of a molecule is affected by the arrangement of electrons, but does not describe that arrangement. The “shape” of a molecule is how the outside atoms are arranged around the central atom. The lone pairs of electrons affect this arrangement, but are not part of it.
