While they’re at it, would it be possible to have an extra one put in? Why be normal? 
One of my aunts has an extra navel, but in her case, the “surgery” was performed quite unintentionally, using a fishhook.
Or where would you put the salt if you want to eat spring onions in bed?
In the documentary Blade Runner, the replicant Zhora has a navel. Replicants are “assembled” from parts and are fully grown at the get-go. (She was less than 3 1/2 years “old” at the time.)
In her case, there was no need to add it to prevent her from being aware she was a replicant as she knew that already. Unlike others.
The replicant Pris is your basic pleasure model so a navel would be expected by her clients for appearance sakes. But Zhora is an assasin. She might have had the navel added before getting the job at Taffey’s club. Given her situation that seems improbable.
The issue with clones, as noted, is that the method of construction decides as to whether a navel is needed or not.
BTW, the Wikipedia article on navel disorders is quite chilling for such a short entry. Some of those conditions require removal of the navel to ensure a permanent fix.
Sounds like urban legend, unless you’ve got a cite. The navel has some cultural significance in Japan. I would guess it’s about as common as bagel-head surgery (google it) and other forms of extreme body modification. IOW, it’s not at all popular; it’s a fringe activity
The more I learn about modern medicine the more I conclude it takes about a million things working right to keep us alive for the next 10 seconds. Much less 80 years.
The laundry list of ways things can go haywire is appallingly long. Gives one the sensation of hanging by the merest of threads while buffeted by a hurricane. :eek: And yet the evidence all around us is it mostly works most of the time. Perhaps, as in so many things, we shouldn’t examine the magic too closely.
Not to mention, how did it come to be called a belly “button”? At the time when they were first named were they all outies?
The British call it a “tummy button”, as they eschew alliteration for assonance.
I like this time of year because you can find good tummy button oranges at the grocery store.
When my ex-wife had reconstructive surgery after a mastectomy, they removed skin from her lower abdomen for the reconstruction. She woke up from surgery with a newly constructed navel. I don’t remember the surgeon even mentioning the navel reconstruction pre-op, and we were understandably too distracted with other issues to think about it at the time. But afterwards, I thought wouldn’t it be cool to have no navel at all? When people asked about your lack of navel you could respond “Oh, I’m not a mammal. I was hatched from a leathery egg.”
Deon Cole (stand-up comic), during one of his performances, notes that most (if not all) paintings and drawings of Adam and Eve depict them with navels - at which point he asks why. 
I hate to be that guy, but if Karolina Kurkova doesn’t have a belly button, then what’s that indentation in her abdomen right where one would expect a belly button to be?
It’s an indentation in her abdomen right where one would expect a belly button to be.
More seriously, an indentation is not a belly button. A belly button is a healed over scar. An indentation is just a low spot in unbroken skin.
This woman, for example, has indentations (aka dimples) on her lower back. But you wouldn’t call them belly buttons even though they look pretty similar to what Kurkova has on her belly.
There’s less tissue naturally in that spot between the umbilicus and the abdominal wall. (The latter itself can be quite thin in that area, leading to hernias in some people.) So there’s not the same layers of fat, etc., that the rest of the belly has under the skin. Take out the navel and you get a depression.
Well, in some people. In others subdermal tissue can fill in and push out giving outies.
Remember, there used to be big blood vessels passing thru the skin and abdominal wall here to connect to the major vessels in the body.
On Barsoom, the human-like Red Men of Mars are hatched from eggs (as are the six-limbed Green Men). They seem to have belly buttons.
Red (Wo)Man with belly buton
A Rykor (described to be a headless, but otherwise “perfect specimen of Red Martian”. Definitely a belly button. Quote from Wikipedia:
Green man with belly button
A Princess of Mars by Edgar Rice Burroughs | headed for alien territory
Green man maybe without (but obscured by sword)
http://www.catspawdynamics.com/images/michael_whelan_2-the_gods_of_mars-cover.jpg
I don’t know if the White, Black, or Yellow men of Mars are hatched or born, and I didn’t see any good pictures, anyway. All I can tell you is to be prepared for a serious fight if you bother any of these guys. They didn’t make Mars the god of war for nuthin’.