The belemnoids were an ancient group of these invertebrates that flourished during the Mesozoic but became extinct at the K/T Boundary. The genus Sepia in this class contains the species with the highest encephalization quotient of any invertebrate and can also change color to match their surroundings. A more notable extinct group of these creatures are the (*) Ammonites. 
The belemnoids were an ancient group of these invertebrates that flourished during the Mesozoic but became extinct at the K/T Boundary. The genus Sepia in this class contains the species with the highest encephalization quotient of any invertebrate and can also change color to match their surroundings. A more notable extinct group of these creatures are the (*) Ammonites. One group of animals within this class has a notable species called the "blue-ringed", while another group in this class has a largest member called Architeuthis. This class also includes the Nautilus and the Cuttlefish. For ten points, name this class of mollusks that includes squids and octopus.
The belemnoids were an ancient group of these invertebrates that flourished during the Mesozoic but became extinct at the K/T Boundary.
{Cephalopod}s or {Cephalopod}a