For another type of Ba'ul ship, please see Ba'ul sentry ship.
The Ba'ul harvest a group of Kelpiens
The Ba'ul ship was a vessel used by the Ba'ul to perpetrate their harvesting of the Kelpiens.
Aradar noted that fragments of the ship were sometimes left behind, but "to keep it is forbidden."
When a piece was left in the 2230s, Aradar asked Saru to dispose of the fragment. Instead, Saru clandestinely took the piece apart until he was able to use it as a communications beacon – eventually reaching out and being heard by Starfleet Lieutenant Philippa Georgiou. Georgiou noted it was extraordinary that Saru, a member of a pre-warp civilization, was able to use the device. (ST: "The Brightest Star")
This ship was only mentioned in dialogue.