The Alien Virus Canister (more often simply referred to as the "Goo Jar") is a special object that can only be found in the level Caduceus in Viscera Cleanup Detail. It can also be brought to The Office through the use of the Janitor's Trunk.
The Alien Virus Canister appears as a long glass container filled with a glowing green liquid surrounded by a metal framework.
- Each Alien Virus Canister must be incinerated before punching out in order to obtain a perfect score.
- When dropped or otherwise impacted at a high enough speed, the alien virus canister will shatter and spread its contents across the nearest surface. The resulting green puddle of goo is unlike other messes in Viscera Cleanup Detail in that it glows bright green in dark environments.
- If shattered on top of a corpse, the corpse can become "stained" with a green liquid. If the corpse in question has been split into multiple pieces, all of which are in their original positions, they may become "glued together" and fuse into a single piece.
- The virus within the Alien Virus Canister is credited by several documents found in the level and several other Ending Messages related to the subject as having the ability to transform both living and dead tissue into a sort of sponge, effectively reanimating it. It should be noted however that this cannot happen during the course of normal gameplay.
- A variation of the standard Alien Virus Canister can also be found within the game files half-filled with clear fluid.