Water, carbon dioxide, and oxygen are among the few simple molecules that can cross the cell membrane by diffusion (or a type of diffusion known as osmosis ). Diffusion is one principle method of movement of substances within cells, as well as the method for essential small molecules to cross the cell membrane.
I think its c.trace fossils because this is an print of an organism that was of the animal, but produced from them, which means it could be put on a rock.
