Shoulder is the most mobile joint in the human body. The ball joint can rotate around 3 axes, so it alone provides our hands with almost 50% of their mobility. This is all the more impressive when one considers that all that movement must not impede blood flow through the appendage.

One of these bones is not like the others, one of these bones does not belong.

It is clavicle. Clavicle is dermal bone, so it develops by a different process than most other bones. This means it has different internal structure and is therefore more fragile. Broken clavicle is therefore a fairly common injury.