Ba'ul sentry ships with active weapons
The Ba'ul sentry ship was a type of starship used by the Ba'ul to defend their homeworld of Kaminar. They were much larger than a Federation Crossfield-class starship, and featured multiple weapons emplacements that extended outward when active.
In 2257, the Ba'ul High Council sent ten sentry ships to surround USS Discovery, to reinforce their demand that Commander Saru be handed over to them. The ships stood down and returned to Kaminar after Saru surrendered himself. (DIS: "The Sound of Thunder")
This vessel was originally a "Ba'ul culling ship" before the episode story changed. Some of the earliest concept designs for it were inspired by The War of the Worlds. [1]