For those of us who have “innie” belly-buttons, what is keeping our belly-buttons “pulled in” that causes them to stay indented on our stomachs without eventually flattening out?
In: Biology
As you might know the belly button is what is left of the main blood vessels (and other important tubes) that connected a baby to the placenta of the mother. As that tube stops being useful it basically shrivels and turns into a tendon. This tendon connects the outer skin layer to the inner layer of the abdominal cavity. That is what is “pulling” the innie belly button down. I can also try explaining why outies happen (spoiler alert umbilical hernias) but i am trying to keep this as eli5 as possible. Let me know if you have any other questions.
Also fun fact. Belly buttons can fail to close and leave a tube connecting the bladder to the belly button and pee comes out (patent urachus).
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