Kind of. It's when the abdominal wall behind the belly button doesn't heal completely after the umbilical cord is no longer there. It's common in babies, but usually heals on its own. My son had one (since healed) but my doctor told me that if it wasn't healed by the time he was 3 years old, they would have to surgically correct it. It's also seen in animals, and usually happens when the mother chews the umbilical cord too short after birth.