The Sphynx is a massive stone statue that appears in Super Mario Odyssey. He appear across several kingdoms, usually blocking the way to a small area where Mario can obtain a Power Moon.
These statues will move once the player answers its riddles, which are often related to the kingdoms in which they are present. After the secret pathway has been opened, the Sphynx will ask additional questions. By answering all of the Sphynx's questions correctly, an achievement will be unlocked from Toadette in the Mushroom Kingdom, which grants Mario a Power Moon.