From Halopedia, the Halo wiki
It is represented by a silver six-pointed star with a purple MJOLNIR helmet with outward-pointing spikes.
- There was a similarly named medal in Halo 3, Unstoppable, awarded for a 10 kill streak as the Juggernaut. In Halo: Reach that medal was renamed Immovable Object.
- The name of this and the Immovable Object medal are a reference to the physics question/joke: "What happens when an immovable object meets an unstoppable force?"