Nautilus is a marine cephalopod known for its distinctive spiral-shaped shell, which is divided into multiple chambers. Nautiluses can adjust their buoyancy by regulating the gas content within their chambers, helping them control their depth within the ocean and avoid predators. Nautilus is found in the tropical waters of the Indo-Pacific region, including areas such as the Philippines, Fiji, and Australia. Nautilus has a long evolutionary history, dating back over 500 million years, and is considered a living fossil.