I have an idea about cicadas.
Specifically, this SCP would be about a subspecies of cicadas that are completely undetectable by any sense. However, this isn't a method of camouflage from the cicadas themselves, it's instead caused by a cognitohazard associated with a knowledge of stars. So anything that has knowledge of what stars (including the sun) are1 can't see, feel, or otherwise sense these cicadas at all. This effect extends to their droppings and molten skin as well. Since a good portion of cicada predators are affected by this cognitohazard, this means that this subspecies is pretty populous, and is able to thrive in massive numbers.
The problem is that I don't really know where to go with this. I'm planning on putting in an addendum where the Foundation is able to amnesticise some D-Class to be immune to the star cognitohazard, leading to the realization that there are however many billions of these things all over the place. I don't really have anything past that, though. Another big problem I have is that, logically, a ton of invisible cicadas would be pretty hard on the environment. So, maybe it doesn't even need to be cicadas. Maybe it could be maggots, cockroaches, or something else small and inconspicuous that would add some creep factor. Admittedly, I don't really know anything about cicadas, and I'm not too great at writing biological SCPs, so I'm up to change whatever needs to be changed.
It's kind of a silly idea, but let me know what you think.
