No, Facebook isn’t planning to limit your news feed to the posts of just 26 friends. To the contrary, the social media network has announced pending changes to its algorithm that will “prioritize posts from friends and family over public content”—that is, more status updates from your cousin or your college roommate and fewer articles like this one. At the moment, this change may seem like a mixed blessing, especially if your feed, like mine, has been overrun with bogus “26 friends” posts from cousins and roommates during the past few weeks.

As Facebook hoaxes go, “26 friends” is pretty routine. It calls on the poster’s friends to leave a comment, thereby assuring that they’ll bypass the nonexistent filter. Some Facebook hoaxes are perpetrated by phishing scammers and “like farmers,” but even more seem, like this one, to have no purpose at all. Anyone tricked into reposting the warning or commenting on their friends’ posts has nothing to lose but their dignity. And who knows? Perhaps even the original person to post about Facebook’s 26-friends limit truly believed it to be real. Instead of calling them hoaxes, it might be useful to think of them as an entirely new category of falsehood: the Facebook algorumor, a viral panic about some untrue change to Facebook’s policies that spreads in part because posts about the rumor itself create the kind of engagement Facebook loves to reward.

In the 14 years it has existed, Facebook has spawned scores of algorumors, enough viral scare campaigns to sketch a shadow portrait of the network. This isn’t the Facebook that privacy advocates and media analysts warn us about, although every so often the two overlap. This isn’t the Facebook that actually exists at all. This is a Facebook of our imagination, a force that shapes our world and yet remains enigmatic in the face of our pleas and invective. Who can fathom its whims? As with a capricious pagan god, it demands the tribute of our likes and shares, and in return it promises us nothing—except when it’s offering us a $5,000 cash reward from Bill Gates.

Like most gods, this shadow Facebook has been patched together out of confirmation bias, wishful thinking, chance, and paranoia. It is imperious and unpredictable. It wants to commandeer the copyright for your cat photos and bestow share-induced riches upon cancer-stricken children. It has cleverly filled its corridors with hidden followers, people it has hired to “stalk” us, yet it will reveal their identities to us if we only type the magic words “automation labs” into a search window. In its arbitrary judgment, the shadow Facebook has deemed a photo of an amputee veteran or a Norwegian cartoon mocking Donald Trump or a painting of a nativity scene to be “offensive” and a “violation of community standards,” and it will only change its mind if enough people like and share the image, which is inexplicably still shareable despite being banned. Shadow Facebook is this far away from prohibiting swearing and will shut down any account engaging in profanity, casting its owner into permanent exile. Any day now, shadow Facebook will start charging users to keep their posts private or to use the site at all, but you can escape this fate by copying this post to your wall, whereupon “your icon will turn blue and your Facebook will be free for you. Please pass this message, if not your icon will be deleted.”

Algorumors are so manifestly fake, pocked with misspellings and ginned up with pseudo-official language. The profanity ban, says a meme purporting to be a statement by Mark Zuckerberg, is “due to new laws issued by our legal department.” “Though we can’t imagine it needs clarifying,” Snopes.com explained in debunking the hoax, “Facebook does not have the legal authority to create laws in the United States or anywhere else.”

Yet people fall for this stuff over and over again, in part because it almost seems like Facebook does have such powers, or the next best thing to them. The real Facebook is still living down its role in spreading fake news that may have been instrumental in deciding the 2016 presidential election, after all. We know, vaguely, that the social network is constantly rejiggering the sorts of posts it foregrounds in our timelines. Meanwhile for many older or less technologically fluent users, Facebook serves as the primary portal to the internet, where more and more of our social reality lives. Put a comment on my post, someone in my timeline implored during the peak of the 26-friends scare, “otherwise Facebook chooses who I see and I don’t need Facebook to choose my friends!” But of course Facebook already does choose what we see, and all we have with which to placate the strange and unknowable algorithms that govern it is the ritual magic of our likes and shares.

Shadow Facebook is the Facebook of our fantasies and the Facebook of our fears. Shadow Facebook knows you are hooked, and it’s getting ready to reel you in. It wants to empty your wallet and steal your thoughts. It can control what you are allowed to say and how much you are permitted to learn about the people in your life. It knows more about you than even Santa Claus should, and its invisible minions are everywhere. It doesn’t quite exist, but like all shadows, it’s the same shape as something real.