Which part of the bone that bump is visible to each side of the lower abdomen?

The bumps visible on each side of the lower abdomen are likely the iliac crests, which are the top edges of the ilium, the largest bone in the pelvis. These bony prominences can be felt when you place your hands on your hips, and they play a crucial role in providing structure and support to the pelvis. The iliac crests also serve as attachment points for various muscles and ligaments in the abdominal and hip regions.