Small children often want to know why we have a belly button.
In fact, who doesn't love to indulge in a bit of navel-gazing, comparing their own navels to those of their friends? It's when we feel deficient in the belly button department, either because ours is too small, too big or even non-existent, that our navel-gazing turns to neurosis.
Good thing, then, that such a procedure as umbilicoplasty exists.
It's plastic surgery to reshape the belly button into a more desirable or aesthetically pleasing appearance, and it can be carried out in about an hour using only local anesthesia.
The beauty part is that it leaves virtually no scars, is relatively cheap and almost always has permanent results.
What's not to like? Some people, however, appear to have no belly button at all, with Czech supermodel and underwear model Karolina Kurkova being perhaps the most famous contemporary example.
What is a Belly Button? A belly button is the scar we humans - and all mammals - are left with after spending around nine months in our mother's womb.
The scar defines the place where the umbilical cord attached us to the placenta, which nourished us while we were in utero.
The depression (pit) in our tummies is signifies where the cord was attached to the underlying fascia.
When we are in the womb, we don't breathe air or enjoy gourmet three-course meals.
In fact, we don't even drink our mother's milk.
Instead, all the nutrients we need - as well as oxygen - are delivered through the umbilical cord, which is attached to the placenta.
This organ, unique to mammals, attaches the baby to the uterine wall.
As well as nourishing us, the placenta also allows waste to be removed, via it and eventually the mother's kidneys.
After the baby is eventually delivered, the placenta is delivered as well.
Bye bye, placenta.
Hello, baby! Hello, belly button! Innie vs Outie vs Alien Appearance Sometimes, when the baby's umbilical stump drops off and heals, little Junior is left with a navel that fails to please - usually referred to as an "outie".
The debate concerning innies vs outies is ongoing, with the majority of humans preferring the former.
We usually have outies due to extra skin left over from the umbilical cord, although sometimes they are the result of an umbilical hernia.
This occurs when part of the intestine protrudes through a part of the intestinal wall that is weak, and is a harmless condition that can be easily fixed.
Some people, however, appear to have no belly button at all, with Czech supermodel and underwear model Karolina Kurkova being perhaps the most famous contemporary example.
Ms Kurkova, for all intents and purposes, appears to have a smooth, slight indentation in place of a navel.
She will not comment on how this came to pass, but her agent has assured inquisitive members of the press that she is not an alien.
Most people who seemingly have no belly button either had surgery to correct problems such as an umbilical hernia, or were born with a condition where the intestines and stomach poke through a hole in the abdominal wall, which needs correcting, usually soon after birth.
Other people lose their navels as adults, following skin grafts or other types of stomach surgery.
Many decide to have umbilicoplasty to rectify the situation, and either give them a new belly button, or bring their outie back in.
Others, such as Kurkova, prefer to keep the Martian look.
Umbilicoplasty: The Basics In most cases, umbilicoplasty is a very straightforward procedure.
Extra skin from the belly button area is taken away to reshape the navel.
The clever bit is that the scars are carefully hidden, so that the operation is not obvious to the naked eye (unless you look very very close).
Some people choose umbilicoplasty for reasons mentioned above; another fairly common reason is because of dramatic weight loss or pregnancy, which can change the shape of a belly button.
Please be aware that if you do get pregnant following the operation, or gain a large amount of weight, the results may not be what you intended.
If you have no belly button - or if you have a tummy tuck which requires a new naval to be formed - then your plastic surgeon can easily create a new one.
A new outer hole for the naval is cut out, then the stalk of the belly button is brought forward and sewn into place.
Some people opt to have to have the stalk kept short so the outer skin will pull it down, creating a belly button that appears more youthful.
Discuss your requirements with your surgeon beforehand.
If you do choose to have belly button surgery, make sure you use only a Board-certified surgeon, or the equivalent.
The operation is fairly minor with few side effects, and most people can even return to work the same day, or the following day.
As the sutures are dissolvable, there is very little follow-up care needed.
Marvelous Midriffs As baring midriffs is becoming more fashionable - along with belly button piercings - cosmetic surgeons are seeing an increase in the number of people opting for umbilicoplasty surgery.
In fact, many offer to pierce the belly button at the same time.
Some people opt for a tummy tuck, or abdominoplasty, as well, to make the entire area look more svelte and sleek.
According to the New York Times, the rise in umbilicoplasty surgeries shows the "cultural triumph" of the midriff.
"Hidden for decades, the navel is now the center of what's considered sexy, flaunted in a wave of stomach-baring outfits and above-the-fold news articles pondering Britney Spears's bellybutton," it said in an article about umbilicoplasty.
It said that "about a third of college women" have chosen to pierce their navels.
Belly Button Organ Extraction These days, belly buttons are not just to nourish babies or look good pierced.
A London surgeon has pioneered surgery to extract organs through this tiny orifice, leaving virtually no scar.
Mr Barry Paraskeva uses laparoscopic keyhole surgery to remove organs such as the appendix and gall bladder through the navel.
Based at the Imperial College London Healthcare NHS Trust, he claims to be able to remove an appendix in just 20 minutes using his procedure - and allow his patients to return home the same day.
"Having a single access port minimizes the discomfort to the patient, reduces the risk of infection and because the incision is through the belly button, the surgery is scarless," he recently said in an interview with the BBC.
Similar techniques are now being worked on to take organs out through other bodily orifices considered more "natural" - such as the rectum.
The information in the article is not intended to substitute for the medical expertise and advice of your health care provider.
We encourage you to discuss any decisions about treatment or care with an appropriate health care provider.