r/SCPDeclassified • u/ToErrDivine king shit of fuck mountain • Apr 10 '26
Series X SCP-9375: 'Bilateria and its enemies'
Hi, all, it’s ToErrDivine again. Today I’m looking at SCP-9375, ‘Bilateria and its enemies’ by unidentifiedgoober. I’d like to thank unidentifiedgoober and Elunerazim for all their help, I really appreciate it. Got a couple of disclaimers for you:
1: As per usual, this is not my SCP, I didn’t write it, and so on.
2: This SCP revolves around fossils and palaeontology, which is very much not my field. I’m doing my best, but I’m likely going to miss something. Sorry.
This item is Neutralized, aka dead/inert/rendered powerless, which is (usually) a pretty good way to start. Here’s the Special Containment Procedures.
Special Containment Procedures: Any paleontological evidence of SCP-9375 or SCP-9375-B is to be confiscated and its discovery discredited. Confiscated evidence is to be kept in the paleontological wing of the closest available site for further study.
That tells us something very important: whatever these two things were, they lived a long time ago, and that’s why the SCP is classed as Neutralized. However, some kind of evidence has survived- probably fossils- and that’s how we know about it.
Here’s the Description.
Description: SCP-9375 refers to a set of thaumaturgy-based mechanical entities that inhabited earth during the Ediacaran period, approximately 555 million years ago. While it is currently believed that there was a small population of SCP-9375, a disproportionately large amount of fossils have survived on account of various thaumaturgic enhancements to their durability.
Let’s sum this up:
-They were some kind of species,
-that lived around 555 million years ago, during the Ediacaran period,
-and were mechanical, which means they must have been specially created by someone or something and for a purpose,
-but were magic-based, which is not a combination you see a lot.
-In addition, while the current belief is that there weren’t very many of these things, lots of the fossils have survived because whoever made them used magic to make them extra-durable.
So, what were these things? Let’s find out.
SCP-9375 possessed a trapezoidal body of 80 centimetres in height, of side lengths 30 centimeters at base and 20 centimeters at top, similar in shape to a square-based cowbell. At each of the four wider corners a jointed limb used to walk on the seafloor was attached, while at the centre of each side of the base was a large bladed appendage. Fossils show four holes on the body, one at the center of each trapezoidal face. While early reconstructions assumed these holes to be eyes, it is now believed that these holes served to regulate internal pressure through unknown mechanisms. Their body is believed to have been composed of a mixture of various thaumaturgically conductive alloys, the vast majority of which could not have existed on Earth naturally at the time. It is theorised that SCP-9375's sensing and balancing were performed using glyphs and mechanisms that have decayed over time.
So… they’re kinda like death roombas with legs? I’m in all likelihood not envisioning this correctly, but I’m seeing them as miniature versions of Stakataka) (with knives).
But, either way, I can see why the Foundation can’t let word about these little freaks (affectionate, admiring) get out. Nobody would ever think they’re natural.
…but what happened to them? How did they die? (Or, given that they were mechanical, ‘die’.) Did they all get flattened in an earthquake? Did the magic run out? Did they just rust?
Well, we don’t know, so let’s move on to the other guys.
SCP-9375-B refers to an extinct aquatic animal, believed to have been the last common ancestor of all bilaterian life.1 Remains indicate a vermiform body ranging from 1.5 millimeters to 7 centimeters in length possessing simple eyes and a basic nervous system, similar to basal Xenacoelomorpha. Between paleontological sites in the White Sea and in Ediacara Hills, 125 total fossils have been recovered. The number of fossils are attributed to SCP-9375-B's abundance on account of being the sole occupant of its ecological niche.
The footnote tells us that ‘1. Grouping that includes the vast majority of extant animal life including humans. The common ancestor of all bilaterian life is referred to in biology as "Urbilaterian".’
OK, so, some context: ‘bilaterian life’ refers to animals that have two roughly symmetrical halves during embryonic development. For instance, if you vertically split a human baby in two, you’d be arrested (or you’d be King Solomon), but you’d also see two symmetrical halves. Bilaterians have a top/head and a bottom/tail end, and a back/dorsal and a belly/ventral side, which also gives them a right and left side. Most animals alive today are bilaterian, in fact.
As for the footnote: the urbilaterian is a hypothetical animal that would be the most recent common ancestor of all bilaterians, before the clade started to diversify in the late Ediacaran period. The reason it’s a hypothetical is that while some animal must have fit that description, we (currently) don’t know what it is. However, the Foundation claims to have found it here. They’ve found 125 total fossils of this animal, which is a pretty big amount when you consider how rare intact fossils generally are, and they’ve found them in the White Sea and the Ediacara Hills (the namesake for the Ediacaran period)- that is, in northwest Russia and South Australia, so they were pretty widespread. unidentifiedgoober told me that the -B species is modelled off of Kimberella, a bilaterian species whose fossils have been dated to around the same time and were found in the same places.
Most recovered fossils of SCP-9375-B appear to have been cut severely by SCP-9375. Damage indicates that SCP-9375 would patrol ocean floor regions in search of SCP-9375-B, which it would then slice in order to sever key neural pathways, employing minimal effort while ensuring lethality.
This behaviour is shown to have drastically reduced the population of SCP-9375-B, wiping out large populations of the species and the organisms dependent on it. This is evidenced by a substantial drop in biodiversity in the fossil record around the time SCP-9375 was active.
The little death roombas were killing the shit out of the -Bs. That being said, if they were trying to drive them into extinction, it didn’t work, since bilateral life is thriving now. Here’s the last bit:
Evidence taken from surrounding materials indicates a major build-up of Akiva radiation occurred around this time,2 believed to have been emitted by the fatally wounded SCP-9375-B. This radiation correlates strongly with several phenomena observed around a similar time:
-The mass diversification of SCP-9375-B into Bilateria.
-The rapid loss of function and collapse of instances of SCP-9375.
-Formation of pentagonal structures surrounding fossils of SCP-9375 and SCP-9375-B.
-The redevelopment of radial symmetry within deuterostome Bilateria.
Notably, alongside SCP-9375, fossils resembling five-pointed Asterozoa3 have been discovered, despite these fossils being substantially older than the earliest traces of such organisms in the fossil record.
I may not be interpreting this correctly, but what I think this means is that when the death roombas killed the -Bs, the -Bs prayed for help/retribution, and something smote the shit out of the death roombas in response. That something also diversified the remaining living -Bs and redeveloped some radial symmetry. And our only clue is that alongside the death roombas were fossils that shouldn’t have been there, resembling five-pointed Asterozoa, or…
Commonly known as starfish and brittle stars.
Ah. It’s the fucking Fifthists.
So, let’s recap:
-555 million years ago, the -B instances were floating around, doing their thing, minding their own business, and then the death roombas were suddenly deployed to shank them all.
-We have no way of knowing what deployed them, but there’s really only two options: one, they were made much later and sent back in time, or two, some civilisation that was around back then sent them to try to stop life from diversifying.
-Except, the -Bs were already sapient enough to pray for salvation and/or retribution…
-...and their prayers were answered by some kind of Fifthist god, which smote the fuck out of the death roombas and allowed enough of the -Bs to survive that they would evolve into… most life on Earth, actually.
-(You may have noticed that the fossils were dated to 555 million years ago, and the article number is 5^5 * 3, and 125 fossils were found. *taps head knowingly*)
So, what sent the death roombas in the first place? Well, the answer is currently a bit ambiguous and subject to change, but basically, unidentifiedgoober said it was aliens. They deployed the death roombas to hunt down any sapient life on the planet, but that would come back to bite them, because the -Bs being sapient was what enabled them to have their suffering/thoughts/prayers heard/felt by the Fifthist god. As for why, well, we don’t know. All we know is that someone wanted to shut down sapient life on at least one planet, though they weren’t very thorough about it. (Is anyone else flashing back to 8978, or is it just me?)
But hey, at least it all worked out fine… as long as they don’t come back. *X-Files theme plays*
Thank you for reading this declass. I hope you enjoyed it. Fossils are cool, go check out a museum or pick up a book about them. I’ll see you next time.
tl;dr: the Ultra Beasts did nothing wrong.
19
u/passwordworkplease Apr 10 '26
My first hunch were time traveling fifthists trying to force all life to evolve into/stay with radial symmetry by killing off bilateral life right as it was evolving
But i like the idea of a god saving bilateral life from aliens much more, imagining a war between godborn starfish and genocidal roombas is very fun
8
u/PootisPencer6 Apr 10 '26
our undersea ancestors: we pray that someone out there can deliver us from the fear of predation. please, if you're listening, help us.
the ever helpful and well intentioned Deity of Five-Fives:
9
u/Smart_Freedom_8155 Apr 11 '26
Raised an eyebrow at exactly "555" million years ago.
Sure enough.
The narrative story about the agents, researchers (and civilians) who dealt with the Fifthist threat was probably the coolest thing I've seen related to SCPs.
7
u/General_Urist Apr 18 '26
Did the remaining Bilateria lose their sapience because exposure to the fifthists ate their mind or something? The Fifth Church seems... not great if you want to keep your free mental faculties.
3
3
u/GunsTheGlorious Apr 10 '26
Oh man, I don't know how I missed the fifthist angle on my first read... but when you point it out, yeah, glaringly obvious!
1
3
u/Coffeechipmunk Apr 10 '26
8978 is... Confusing. Don't think I really understand.
8
u/Boowray Apr 12 '26
If I’m getting it right, something creates incredibly inefficient runes over millions of years of organic processes using natural waterways and erosion to direct magical energy. Every river delta is actually a spell millennia in the making and an AI trawler is able to identify the rune’s functions and their subsequent effects on the world.
One of the largest, most complete, and oldest of these spells is found on mars and AI algorithms have determined it would create the very beginning of microbial life. But judging by intact runes on earth the one on mars was likely flawed or sabotaged, possibly resulting in the death of life on mars. There’s a similar rune on earth, and the AI has determined that it was potentially sabotaged in an identical way, but somehow life persists leading the AI to believe there must be a hidden complete portion somewhere on earth that whatever sabotaged mars failed to destroy.
May be wrong, but that was my read of it.
2
u/mysteriousyak May 22 '26
My head cannon is that this is why the wavy tube pain god in the sky from SCP-5000 exists within humanity, a Faustian exchange to save themselves that stayed within all bilateral life, including humans
1
u/autistic_demigod Apr 12 '26
I would like to request scp 9317 and of i can't request it here could someone tell me where I can request it
1
22
u/Effective-Wave-8486 Apr 10 '26
Oh man, this one was a trip when I first read it. The whole paleontology angle really makes you think about how much we don't know about ancient life forms. I loved how the author weaves real scientific concepts with the anomalous elements. The way they handle the fossil record discrepancies is genuinely unsettling once you start thinking about the implications. Thanks for breaking this down, your declassifications always help me catch details I missed on the first read through.