Saphira's eye from the book. Speaking of, the book is so much better than the movie! The people who made the movie completed butchered such a beautiful story! Maybe if they'd stuck to the book, we'd have the others turned into movies as well!
Lions are nocturnal creatures, and are a symbol of authority and command over subconscious thought(as night is an ancient symbol of the subconscious - or dream states). The lion is considered by many ancient cultures to be a solar animal judgment.