Per 
Item #: SCP-XXXX
Object Class: Euclid
Special Containment Procedures: SCP-XXXX is kept in a 9 by 3 meter room. The containment cell of SCP-XXXX is the same room SCP-XXXX was found in, the room has since been modified. The walls of the room have been painted white and the windows have been covered by steel.The corner of the room where SCP-XXXX resides must be lit up by three or more extremely bright lamps and must be directly shone upon SCP-XXXX. If the light inside of the lamp dies they must be replaced no more then 5 minutes after the light dies. When replacing the light an extra lamp must be temporally put up. The windows of SCP-XXXX containment cell must never be opened under any circumstance.
Description: SCP-XXXX is a shadowy mass residing in an abandoned house in the middle of ████████, USA. SCP-XXXX stretches 1 meter out and is approximately .75-1 meter in height on both sides of the wall. SCP-XXXX appears to be just a shadow in the corner of the room but when light is shined on SCP-XXXX it does not change in darkness or size. During the night SCP-XXXX grows in size. It was estimated it grows about 0.01 inches per night but due to prevention from the SCP Foundation they have stopped SCP-XXXX from growing by shinning light upon it.
When SCP-XXXX was first interacted by the SCP Foundation, personnel stuck a flashlight into SCP-XXXX. There was no affect upon SCP-XXXX. When the flashlight was pulled out of SCP-XXXX the flashlight had a shadow that was the same in darkness as SCP-XXXX. The shadow did not move along with the flashlight but was fixed in one position which was about 6 inches away from SCP-XXXX. 24 hours after the appearance of the dark shadow, the shadow merged with SCP-XXXX, and SCP-XXXX grew in size. After this event the flashlight mysteriously disappeared.
SCP-XXXX is believed to be sentient in some way. SCP-XXXX has reacted in different ways to different vibrations. An example of this when a speaker was place in the containment cell of SCP-XXXX. The speaker played loud music and vibrated the ground with the bass. SCP-XXXX curled into a crescent when the ground vibrated and then back to its original state after each vibration. Other signs of SCP-XXXX possible being sentient is during nights of a new moon Morse code can be heard through taps. When translated it makes no sense but over time it has slowly been making actual words like "hell" or "bright".
Other strange reactions that SCP-XXXX is when purple UV light from a flashlight is shined on it. When that happens SCP-XXXX will try to get far away from the light. When this was first tried SCP-XXXX split into two and quickly moved to the corner inside it's containment cell farthest away from the light. After the light was turned of SCP-XXXX returned to its original position. Other occurrences where SCP-XXXX is during the solar eclipse of 2017. During the time leading up to complete totality SCP-XXXX starting growing rapidly. Despite best efforts the SCP Foundation could not stop SCP-XXXX from growing. At totality SCP-XXXX suddenly covered its containment cell. After totality SCP-XXXX suddenly went back to its original position. In case of a similar event happening no personnel shall be present during the event.
The true identity of SCP-XXXX is still unknown to the Foundation but through testing there are some guesses. Here are some notable test logs.
