Per 
SCP-10912: The Lullaby wall
Classification: Euclid
Description: A plain panel, being both dark and bright at the same time. It will stay hidden in either dark halls or bright corridors, and can withstand both environments without having to change form. When it is hiding, it turns into a solid wall that can shrink in size to crush its victims. The only way to contain it is to wear glasses with special lenses provided by the foundation. These lenses are designed to see it, and when it is seen, it will be temporarily neutralized for 15 minutes. During this time, it is contained in a massive room measuring almost 54 meters so that if a D-class is in the containment, it will take 3 hours to crush its victim. The door to its containment is replaced by a window where it can be viewed. Some events mentioned by several D-class subjects mention how it will sometimes sing quietly to a human… or sometimes even a corpse, as it sooths the withering soul inside the body.
Sometimes it is completely visible, with blood stains splattered on it, waiting as the time of their victim slips away. Another rare event can sometimes happen, where it will say that it used to be a [REDACTED], and that its face was slammed against a wall, as its soul found its way inside the wall.
