There are similarities and differences between the appearance of an alien and a human being. Both aliens and human beings have fragile bodies. If they fall, they could get injured. Plus, it doesn’t take much to cause the death of an alien or a human being. I believe that aliens secrete some sort of fluid if they get hurt.
Humans secrete blood which is precious to the human body and I’m sure that it is needed for their bodies too. On the outside, aliens have eyes, nose and mouth, but they may look a little different. Aliens have an outside skin that protects their bodies, but their skin may be scaly like a fish. It is not smooth like that of humans.
