Nature just keeps doing what works

As an anatomy geek, I was struck by this photograph of a cave. Look at the wall to the right. It looks just like a side view of the ilia, or the hip bone. Do you see the cave-ilium's

1) foramina for the obturator group

2) ischial tuberosity

3) lesser sciatic notch

4) ischial spine

Nature responds to the rules of nature and I guess this applies to the forces of wind and water as well as force and function.