This Book of Hours has the most peculiar shape: its pages resemble lily leaves (the yellow background is a paper sheet used for contrast).

It was made for king Henry II of France, who used it for private devotion – the Book of Hours contained prayers and other short texts, which were read at set times during the day. 

You can view other pages in more detail here

Medieval shaped books are really nifty!
Check out this heart-shaped one. 🙂

Chansonnier Cordiforme (1470s), also known as Chasonnier de Jean de Montchenu. “Cordiform” just means “heart-shaped.” This music manuscript was commissioned by canon Jean de Montchenu, later Bishop of Agen (1477) and Bishop of Vivier (1478-1497), in Savoy between 1460 and 1477.
Link to the whole thing (PDF): [Link]Bibliotheque nationale de France catalog record: [Link]You can listen to the music, recorded by Anthony Rooley and the Consort of Musicke in two parts: [Part 1], [Part 2]