Since nautiloids are such a diverse group of marine animals, that have been swimming in the world’s oceans for close to 400 million years, they come in all sizes. Some had long shells that could reach a length of up to fifteen feet. Others could be just a few centimeters. Todays chambered nautilus grows to about 8 inches in diameter.

Unlike the present octopi with eight tentacles, the Nautiloids that lived during the Ordovician period had more, maybe hundreds.