WHY is the navel concave or convex?

In 90% of people the navel is sunken (hidden inward) and forms a dimple on the abdomen, while 10% of people have a convex navel (clearly visible from the outside).

Congenital anomalies accompanied by a deformity of the umbilical zone are detected immediately after birth. In infants with a cutaneous umbilicus, the skin of the abdominal wall passes over the adjacent part of the umbilical cord.

As a result, after the umbilical cord falls off, a noticeable bulge is formed. As the baby grows, the bulge sometimes retracts, the appearance of the belly button normalizes. However, some patients have a convex navel for the rest of their lives.

@Health