Item #: SCP-186-ARC

Object Class: Euclid

Special Containment Procedures: SCP-186-ARC is contained in a double-walled chamber that must be kept in complete darkness at all times. Entry to SCP-186-ARC's chamber is only possible via a two-stage blast door which opens only when a state of absolute darkness is confirmed by photographic sensors. No light-emitting devices are allowed within the inner chamber.

Examination of SCP-186-ARC may only be performed with prior permission from at least two (2) Level 3 personnel, and may only take the form of somatosensory observation or MRI scanning.

Note: As of the findings detailed in Addendum 186-ARC-01 (see below), infrared and ultraviolet imaging and analysis of SCP-186-ARC are tentatively approved, pending a method can be devised of doing so with zero visible light emission.

Description: SCP-186-ARC appears to be a triangular bi-pyramidal object of unknown composition approximately 30 cm long and 8 cm in width, which bears a single line of indecipherable script on each face. SCP-186-ARC is highly sensitive to light and propels itself at extremely high velocities at the source of any light in its vicinity. SCP-186-ARC is highly dangerous in its active state, as no known material has been shown to be able to contain it while in this state.

To date, no emissions of any kind have been detected from SCP-186-ARC in either its active or inactive state. It is not known whether SCP-186-ARC is intelligent or sentient, but its activity is more consistent with programmed behavior than intelligent thought.

SCP-186-ARC was discovered in [REDACTED] during a routine survey of a cave system by a four-man civilian geophysicist team on ██/█/████. Class B amnestics were administered to residents of the nearby village of [REDACTED] and a cave collapse cover story was established to explain the loss of two (2) residents prior to full containment.

Addendum 186-ARC-01: Additional Handling Information for SCP-186-ARC

After extensive experimentation, SCP-186-ARC has been found to only be activated by electromagnetic radiation in the visible light range. Further testing is pending, but so far it has not responded to any other form of manipulation, and is in fact safe to handle in any way so long as no visible light is present.

As a reminder, however, personnel are reminded that no objects capable of emitting light are allowed in its chamber at any time, as we do not want another incident like the one that occurred with Dr. ███████ and his self-illuminating wristwatch.

- Dr. █████████

Addendum 186-ARC-02: Radio Transmission Transcript from Civilian Geophysicist Team

L██████ (GT-1): "Can you start on the readings for the tunnel up ahead?"

M██████ (GT-2): "Sure thing, make sure-" [Transmission Terminated]

R█████ (GT-3): "What the hell was that glow?"

L██████: "It came from just up ahead, where-" [Transmission Terminated]

C███████ (GT-4): "What's going on up there?"

R█████: "I'm taking a look, I saw two flashes. L██████ and M██████'s radios cut ou-" [Transmission Terminated]

C███████: "Oh my God-" [Transmission Terminated]

End of Transcript

Addendum 186-ARC-03: Autopsy Report of M██████ A███████ (Geophysicist Team Member 2)

There is a perfectly triangular column of matter missing from the head lamp to the back of the skull, none of which was recovered from the scene. Internal injuries are consistent with extreme high-temperature vaporization, and a 'flash mark' was found on forehead, also consistent with internal burns.

Some strange markings were noted, seared into the inside of the wound. These are not consistent with the markings on SCP-186-ARC itself, and appear to form the word '███' when extrapolated to a flat plane. Further research recommended.

Cause of death is determined to be instantaneous and high-temperature destruction of brain tissue, with entry and exit wounds as noted. No other injuries found.

Dr. █████