What is your bellybutton connected to as an adult?

Nothing! The bellybutton is essentially scar tissue (left over from the neonatal umbilical cord) that is fused with the abdominal wall. There are some pediatric surgical problems involving remaining attachments to the umbilical stump, but normally the belly button is not "attached" to anything. In fact, many laparascopic surgeries use the belly button as an entry point into the abdomen.
The liver. During fetal life, the umbilical vein returned from the placenta, entered the body at the umbilicus and coursed to the liver to connect with the vena cava. After delivery, that vessel collapses and becomes known as the ligamentum teres. The ligamentum teres is present throughout life, essentially tethering the umbilicus (belly button) to the liver.
None no connection. It gets dirty just clean it when you take a bath.
None no connection. It gets dirty just clean it when you take a bath.
None no connection. It gets dirty just clean it when you take a bath.