This is a real nautilus shell! It is available exclusively in Canada! They measure roughly ~6" long.
The chambered nautilus is a marine mollusc found on the deep slopes of Indo-Pacific coral reefs. They are living fossils, and have remained unchanged for millions of years!
Amazingly enough, these animals move through the water utilizing a natural form of jet propulsion! This is done with an organ known as a hyponome.
The nautilus has a prominent head, armed with parrot-like beak, and up to 90 tentacles! As the nautilus outgrows its living chamber in the shell, it will actually create new, larger, chambers in a stunning logarithmic spiral! These cephalopods will then seal off the outgrown compartment and convert its use to buoyancy.