There is No Antimemetics Division, by qntm

I really enjoyed reading this. It's a fun-to-read science fiction novel that balances narrative and novelty really well.

In this book, there is a group of people that study the field of antimemetics. An object can be said to have antimemetic properties if it resists being remembered by observers. This object could be a building, a concept, an animal with a unique sort of camoflauge, anything. Upon observing this object, your mind will be unable to generate any sort of memory or even an impression of it: as far as your mind is concerned, it doesn't exist (except it does).

Imagine a predator with antimemetic properties, maybe a snake of some kind. This snake might have antimemetic properties that make it unobservable to a human - you may have been near, touched, or stepped on a countless number of these things, but you'd be unable to form any sort of memory about them. This is very different from them being invisible. More terrifying might be an antimemetic venom they have to defend themselves with: upon biting a victim, the snake may poison the individual with antimemetic properties that make them unobservable as well, preventing anyone from getting wise to the snake's existence. More incredibly, this may include a retroactive undoing of any memories or evidence that the victim ever existed. For example, if your mother went on a walk and was bitten by one of these things, she wouldn't just disappear from the face of the Earth - you'd also rationalize a reason for them to be missing or never having existed in the first place (e.g. mother died when I was young, was an orphan, etc.). Strong antimemetic properties may even make it difficult to document - descriptions and accounts of the creature may slip your mind or " corrode" over time.

...And it just gets wilder from there.