An invulnerable player, in and out of Morph Ball mode.
Invincible Mode, or Invulnerability, is a power-up that can be collected from a Randomizer in the Metroid Prime 2: Echoes multiplayer. When collected, it renders the user indestructible for a short period of time. Shots and attacks bounce off of the user while the powerup is active, and Hacker Mode will have no effect on the user. Invulnerable players are colored a shiny gold, which turns silver if they enter Morph Ball mode. It is still possible to kill a user who has entered Invincible Mode - if a participant in a match on Sidehopper Station comes into contact with a Kinetic Orb Cannon while it is firing, they will be killed even if they are "invincible".
The Shield power-up in the Blast Ball mode of Metroid Prime: Federation Force is similar.