This fascinating piece is cast from a SEA URCHIN MOUTH. It is the skeletal structure inside the shell. Comes on a 30inch sterling silver chain with gold plated tips. It is also known as Aristotles Lantern, to find out more read my blog. https://jenniferkinnear.com/blogs/news/aristotle-s-lantern. Available in Silver, Silver/Gold Plated Tips & Gold Plated Silver.