Per 
SCP-5237 before "The Disaster".
Item #: SCP-5237
Object Class: Safe Euclid Kušum
Special Containment Procedures: SCP-5237 must be contained in a 30cmx30cmx30cm glass box closed with a digital lock. The glass box is on a "nightstand" inside a containment chamber.
SCP-5237 is now contained inside a steel containment box, with 4cm thick walls, being 1mx1mx1m. The nightstand was removed, and the steel containment box is now placed on the floor of the containment chamber.
SCP-5237 containment is a large room, with walls that absorb light and sounds. The room is 5mx5mx5m and has a catwalk attached to every wall. NOBODY may enter the containment chamber.
SCP-5237 containment is a room with soundproof walls that absorbs light too. The dimension is 15mx15mx15m. Any contact with the SCP is extremely forbidden.
SCP-5237 containment is now unknown due to the detonation of the nuclear warhead.
Description: SCP-5237 is an anomalous tennis ball, with a diameter of 6,54 cm. The SCP looks like any normal tennis ball, it has the same circular shape, the same material, and the same colors. It has a mass of 60 g and has a bright yellow color. It has a nylon shell as the outside. It's not extremely new, and you can notice that the SCP got used more than once. One of the properties of SCP-5237 it's its indestructibility, making it possible for the researchers to understand what it's like on the inside only through x-ray; on the inside, the SCP has a hollow rubber core, like any normal tennis ball. SCP-5237 can defy the laws of physic: dropping SCP-5237 from a certain height, will make the SCP keep bouncing at that height, ignoring gravity, friction, and so on, and it won't stop until an external force, like a human taking the ball, will occur.
SCP-5237 was bought by a Senior researcher at a █████; The place got under investigation by SCP personnel and ended up getting dismantled on the date ██/██/████. The owner of ███████ has been found dead 3 days after the disaster in a forest near ██████, from a heart attack, with his facial muscles, still contracted in a terrorized face. What caused the heart attack is unknown, but I theorized that is related to an SCP.
Addendum: SCP-5237 started to glow during the nights. The light it emits it's soft. It's around 10 lumens.
Addendum 1: The SCP started emitting a low-frequency white sound, around 34 Hz. The sound seems to be continuous and never stopping, but it doesn't seem to affect anything. The sound is audible only when the listener is at least 10cm close to the SCP.
Addendum 2: Class Ds that had/have contacts with SCP-5237 seems to start developing a weird itchy red stain on the derma of their chest, next to the heart. Medic researchers discovered that it seems a normal irritation, and the only thing that relates to SCP-5237 is that only those who had contacts with the SCP have the symptoms. For safety reasons, those subjects have been quarantined in a room.
Addendum 3: The Class Ds that had been in contact with SCP-5237 are now called SCP-5237-1. Every SCP-5237-1 seems to develop an irritation on the chest, always around where the heart is. Those subjects seem to get worse after 2 months. Every treatment has been tried, but the irritation doesn't seem to go away. After 3 months the SCP-5237-1 will start to have a convulsion. The amount of SCP-5237-1 we have is 7 for now.
Addendum 4: It's been 4 months since the first SCP-5237-1 had first contact with SCP-5237. It seems "he" disappeared. Camera scan and deep investigation seem to not be able to track down SCP-5237-1. After SCP-5237-1 disappeared, SCP-5237 changed. It's bigger now, with a diameter of 32,6 cm now. The containment where it was kept broke, shattering glass around the containment chamber where the glass box was. SCP-5237 was moved to a new containment while paying attention to not directly touch it. The light it emits has increased in intensity and now reached 150 lumens. The sound increased to 120 Hz. Tests on SCP-5237 have been shut down until further notice.
Addendum 5: Even if the tests have been stopped, two SCP-5237-1 have disappeared in 1 week, after exactly 4 months by the first contact with SCP-5237. As I thought, SCP-5237-1 disappearing and SCP-5237 getting bigger are related. After the two SCP-5237-1 disappeared, with 3 days between the disappearance, SCP-5237 got bigger again. His diameter is now 72,4 cm. It weighs around 200 kgs now. It seems the SCP has a lot of compressed mass. The light emission now reaches 500 lumens, making it pretty bright and hard to look directly at. The sound reaches 320 Hz, and even if it's annoying you can work with that. It's not advisable exposure to the white sound for long times.
Addendum 6: A SCP-5237-1 got terminated, hoping that killing them wouldn't affect the SCP-5237. We were wrong. SCP-5237 still grew in diameter, even if the SCP-5237-1 died before the 4 months. The dead body of SCP-5237-1 still disappeared, some hours after his termination. SCP-5237's diameter is now 98 cm. Soon it's gonna start to need more space. Rumors between CDs are starting to spread. SCP-5237-1, in quarantine, are hearing them too. They're scared that they're gonna die. They know it. I'm not gonna terminate them since that will speed up the process. I hope that when all SCP-5237-1 are gone, this will end. The luminosity of SCP-5237 increased to 700 lumens. The light passes through the small holes and the clefts. The sound is now around 470 Hz. We need to wear earmuffs when passing next to it. When we will relocate the SCP, I'll make sure the containment chamber is sound isolated.
Note: A Facility personnel found a dying rat with a red stain on his body. I don't like where this is going.
Addendum 7: It seems that SCP-5237-1, the red stain, is contagious. I wasn't sure before, but now I am. I've introduced a perfectly healthy CD in the quarantine cell of SCP-5237-1, and it seems that he too, is now an SCP-5237-1. The situation is critical. This means that the rat could've infected the entire facility. And even other rats. Even if it's risky, we'll have a rat disinfestation. This means that for every infected rat we kill, the SCP may grow in diameter. The SCP kept growing while all this is happening, and SCP-5237-1s are still dying. In the quarantine, there are just 3 left of them now.
The sound reached 650 Hz, and now the light is extremely intense around 1500 lumens.
Note: The SCP, which reached the diameter of 1,67 m, was moved to a new containment. As I thought, the old one exploded because the pressure of SCP-5237 was too strong. It has been moved to a new containment chamber, where it's not a box anymore, but a large room with 5mx5mx5m as dimensions. On the wall, there are some catwalks. The room is soundproof and absorbs the light SCP emits.
Addendum 8: The rat disinfestation gave us the terrible news. It seems we had a colony of around 100 rats in our facility. 30 of them were SCP-5237-1. Every rat is now dead, and the SCP grew more. It seems that some CDs started feeling itchy. They've been quarantined immediately. We're gonna have a medical check-up on every CD in some days to see who may be infected. We may have to exterminate every CD. For now, our Site director put the Site under complete quarantine and needs the approval of the Ethics committee to terminate every Class D personnel. After the CDs, the facility personnel will attend the check-up. This is a complete nightmare. With all the SCP-5237-1, SCP-5237 has grown in size. It is now 4,2 m in diameter. It weighs around 2000 kg. The light it emits it's so strong that getting in the containment chamber and looking directly at the SCP may give you permanent eye damage. We're talking about around 17,500 lumens. The sound is around 4500 Hz. It luckily got less loud but it's high pitched now. This is a complete mess. We need to neutralize SCP-5237, but the transport of it it's impossible, so we have a closed range of options. We still need the site director's approval.
Note: The site director approved. The SCP-5237-1 is increasing at a fast pace, and it seems even through facility personnel there are some. We have 30 days to neutralize the SCP, if we can't make it on time, every SCP will be moved out of the site, and the nuclear warhead will be detonated.
Addendum 9:
| SCP | Neutralized? |
| SCP-409 | Negative |
| SCP-075 | Negative |
| SCP-213 | Negative |
| SCP-662 | Negative |
| SCP-399 | Negative |
| SCP-343 | Negative |
We've failed. Some SCP just couldn't destroy it, and some others just didn't want to. Some partially neutralized the SCP, like SCP-075, but the SCP would just recreate its own mass. It seems that every SCP that made contact with SCP-5237 to neutralize him didn't get affected by SCP-5237-1.
The 30 days ends tomorrow. I'm packing up my things. While we were testing, the ball achieved a diameter of 10,37 m. The sound it emits is now around 34000 Hz and we can't hear it anymore. The light it emits is so bright that it blinds you just by getting close. After reaching the 4,5 m in diameter the SCP was moved in a containment chamber like the old one, but bigger. 15mx15mx15m. It's enormous. We're gonna leave tonight, luckily I didn't get SCP-5237-1. All the CDs got terminated some weeks ago after the EC gave the consent. The SCPs got transferred a week ago. A lot of facility personnel died. I think it's only my fault. Why did I even test it? I started because I was curious about his properties, like defying the law of physics and indestructibility. How could this end like this? All the personnel that survived is getting split into several sites. I think this is the last time I'll write here.
Addendum 9: Site-██ is now inaccessible. The detonation of the nuclear warhead was a success. Maybe SCP-5237 is still there, in the radioactive wasteland, where nobody can reach him.
Addendum 10: [EXPUNGED]
Addendum extra: Here will be stated the various reasons why the SCP neutralization tests failed.
TEST 1: SCP-409
SCP-409 made contact with SCP-5237. The crystallizing process started after 3 hours. After 15 minutes from the beginning of the crystallizing process, it seems that SCP-5237 is having some sort of reaction. The crystallized parts are now falling apart on the floor. Upon reaching the floor they disappear, like if they just got vaporized. The crack left by SCP-409 has a diameter of 32 cm, and the depth is estimated to be around 21 cm. The crack is healing. It seems that the material that fell off is somehow regenerating, filling the crack, and returning to its normal shape, all of this while the crystallizing process keeps going on the other parts of the SCP. After 5 hours of continuous falling apart and regenerating cracks, it is redeemed that SCP-409 can't neutralize SCP-5237.
TEST 2: SCP-075
SCP-075, rehydrated, is introduced on the top of SCP-5237. The corruption process begins. While SCP-075 is slowly crawling through SCP-5237, his acids are starting to melt SCP-5237.
It's been around 7 minutes. Just like the previous experiment, it seems SCP-5237 is regenerating itself, making the acid ineffective. SCP-075 isn't able to neutralize SCP-5237.
TEST 3: SCP-213
SCP-213 approaches SCP-5237. It touches it with his palm. Through a spectrum is possible to see a new source of light appearing, but with the naked eye is impossible to see, because of the brightness of SCP-5237. It seems that SCP-213 is laying down unconscious on the ground, and 1/5 of SCP-5237 is completely vaporized. After 2 minutes, SCP-5237 is perfectly fine and again, in shape. It seems that his regen rate is 3,3 x 104 per second.
SCP-213 is reputed unable to neutralize SCP-5237.
TEST 4: SCP-662
Mr. Deeds appear after ringing the bell. He is asked to neutralize SCP-5237. He politely declines because "It's impossible.".
Neutralization failed.
TEST 5: SCP-399
SCP-399 is being used by facility personnel with a Level 5 approval. Like the other attempts, SCP-5237 is getting deformed, but it gets his shape and integrity back as soon as possible. The room temperature drops. Upon 10 minutes of testing, SCP-399 is considered not suitable for SCP-5237 neutralization.
TEST 6: SCP-343
SCP-343 rejects to help us with the following reason: "I'm too lazy for that and I don't really want to." Every attempt of making him helping us results in him rejecting. It is impossible to neutralize SCP-5237 through SCP-343.
Interviewed: Site Director ███████
Interviewer: ██████
<Begin log, 02/06/████>
Interviewer: What happened after the Site got closed?
Director ███████: Administration department handled the facility personnel. They sent
researchers where they needed to. And the same for all the other personnel.Interviewer: I see. What about your role? Are you going to be assigned to a new Site?
Director ███████: Me? I'm in a standby position. In the limbo. I've become a ghost. I don't
know what are they gonna do with me.
Interviewer: *Nods* The Site closure is SCP-5237's fault?
Director ███████: *Opens mouth without talking, like if he's gonna speak but at the last
moment thinks it's better not to do so.* Yes. We couldn't contain SCP-5237 anymore, and any
neutralization attempt failed.
Interviewer: Is there any person that has more fault than anybody else?
Director ███████: No. We failed as a Site. We underestimated the SCP. We didn't pay enough
attention to clean our facility. We didn't protect our CDs. We failed, all together.
Interviewer: What happened to SCP-5237?
Director ███████: I don't know. And even if I did, I wouldn't be allowed to tell you. The only
thing I know is that it's still out there. I know it survived. I have enough information to know. That
thing is alive. Maybe O5 will take it and bring it somewhere secret even for the foundation.
Interviewer: The things you're saying are pretty accusing. Are you sure about what you're
talking about?
Director ███████: Yes. I am. And that's not the end.
Interviewer: Tell me more.Loading the rest of the log failed. The servers may be down, try later.
<End Log, 02/06/████>
We fight in the dark so that you can live in the light.
I guess nobody will remember your name if you die in the dark.
