Retains its original name after taming. The Unbroken spawns as a trio of worms, each with a different NPC ID, but only the one with this ID is tameable. They can appear in two colours, and if you're unlucky you may have to kill all of them and wait for respawns until your desired colour appears. Their respawn time is only a few minutes.
Level scaling: Most NPCs will scale with the Hunter's level, within the constraints of their level range. Hunters can tame regular NPCs up to 2 levels higher than them, but can only tame elite NPCs of the hunter's level or below.