Also the totally useless body organ that is called the appendix did have a purpose at one time.
I read a recent study that scientists think that the appendix is meant as a digestive bacterial culture reboot system for when you get sick with something like dysentery and the bowels purge.
Edit: apparently, it's just a theory that it's a reboot system.
WebMD: "One theory is that the appendix acts as a storehouse for good bacteria, “rebooting” the digestive system after diarrheal illnesses."