If it happens to you in the womb, it could threaten your health forever. It could mean that you were conceived with a twin but something went horribly wrong. If it’s visible at a glance, it could mean you will have eyes on you everywhere you go for the rest of your life, through no fault or effort of your own (which could be either a blessing or a curse). Or it could even be a bewildering surprise you don’t even suspect until well into adulthood. That’s just a sample of what having an extra organ means to many people. Here are some of the vastly different effects this has had on people’s lives.