The Nautilus is a marine animal that is closely related to squids and octopi, except that it is enclosed in a shell that is divided internally into a series of progressively larger and larger chambers. The mollusk occupies the last and largest of these cells. As the animal develops and matures, it outgrows its former dwelling. It then builds a new more spacious chamber into which it transfers, after sealing off the space it has vacated with a thin partition called a septum.

Go, A. C. (2015, April 14). Many-chambered mansion. Philippine Daily Inquirer, p. E-4.