HJ3-213 was a Scorpion Tank built by the UNSC. It had a painting of a black circle divided in half with an arrow pointing down on its left front tread cover.
The tank's serial number and symbol can be found in the files of the Halo 2 Vista map editor. However, the tank itslef never appears in the game. It is assumed that it was intended to be one of the three tanks overtaken by the Flood in the level Quarantine Zone, but for some reason, it does not appear, and instead, two of the three tanks will often bear the same ID.