Nautilus. Ever growing, ever changing. Once it grows a new, larger chamber it cannot go back to the previous ones; they no longer fit. It has no choice but to move on. Still, the old chambers are still part of them. Just as we are forced to move through life. Our past still stands and affects who we are today.
Nautiluses are the sole living cephalopods whose bony body structure is externalized as a shell. The animal can withdraw completely into its shell and close the opening with a leathery hood formed from two specially folded tentacles.