The Sphinx was a stone lion that stood outside the British Museum in the late 19th century. In reality, it was a sentient creature, and one of the last remnants of magic left on Earth after humans started moving towards machines and science.
Using a ritual involving candles, blood, and regeneration energy with artron, Missy brought the Sphinx to life briefly. It gave her a riddle that lead to her discovering a circular ley line in London, and let her reach into its mouth to retrieve a ruby that served as the focus. (AUDIO: A Spoonful of Mayhem)