Fesarius class

A Fesarius class star ship, has probably been in existence since before the first federation was formed. They always have a spherical shape, but when a piece breaks off from the hull, it will  consist of lines and spheres. I believe the weapon system is a built of energy emitted from one of the small spheres. They are known to be extremely large. To a Constitution class star ship, it will still fill the screen when at 5000 meters (TOS: The Corbomite Maneuver )