Conversation so far:
which are the smallest bones in the body
The stapes is the smallest and lightest named bone in the human body.
what is the purpose of the stapes
The stapes or stirrup is a bone in the middle ear of humans and other mammals.
where is the stapes located
The stapes is involved in the conduction of sound vibrations to the inner ear.

Question: what is the shape of the bone
Self-contained rewrite: what is the shape of the stapes