The Blob

The Blob is a Monster kept in the Facility. It is not listed on the Whiteboard, but can be seen during the System Purge in a deleted scene.

Physical Description and Attributes
The Blob appears as a massive, shapeless mass of flesh-colored tissue covered in thick red veins and pulsating lumps. The origins about the Blob are unknown, and there is little knowledge about its behavior, since it was not seen at any point during the film. Its possible the Blob could have been a failed scientific experiment or is of alien decent, but these are not confirmed. However, since the Blob is kept in the Facility and can be used to aid in completing sacrifices, it must have some sort of intelligence or sentience. Its lack of organs and biological systems that known animals depend upon would make it immune to injury by ordinary means.

The item that summons the Blob from the Cabin's Cellar is unknown. In the film on which it is based the creature's originated in a meteor (a crashed satellite in the remake) so either of these would be logical choices. A small frozen fragment of the surviving blob was stored in a jar at the end of the remake.

Appearances
The Blob is not seen during the Purge, but it does appear in the cube scene. The Blob is also featured in behind the scenes footage, where, in a deleted scene, it shoots itself out of a bathroom sink and onto a male Facility employee's face. This would mean the Blob was released during the Purge and can navigate through pipes and ventilation systems, making it harder to track and avoid.

Inspiration
The Blob is a direct reference to both the original 1958 film and 1988 remake of The Blob. Similar amoeba-like creatures have appeared elsewhere in science fiction.