The Nautilus is considered by many scientists to be a living fossil. Why? The Chambered Nautilus, also known as Nautilus Pompilius by its scientific name, is the largest and most common of about six species known to exist. It has remained unchanged for over 400 million years. The nautilus is a mollusk and a member of the cephalopod family and lives in deep waters.
Information provided by www.discoveringfossils.co.uk and www.weirdseamonsters.com
Nautilus shells are made up of individual chambers, each growing in size as the creature grows. These chambers are secreted by the creature at a rate of one every four weeks, equal to 13 each year. Using this as a guide a shell containing 26 chambers could be assumed to have housed the creature for two years. Like the nautilus retain their original shell throughout their life. Modern day nautili live in cold, deep water.