A tiny modal train track made of metal which if placed anywhere will begin to "grow" expanding out into a complex modal train track all over the place. All bits of the track if broken will have the same properties. The foundation has no idea where the mass comes from. Once the thing has reached over BLACKBOX meters it will begin to grow small lumps on the tracks which will "hatch" into miniature modal trains which promptly begin to travel the tracks. The nightmare fuel comes from the following:
1. It grows constantly. Given time it could bury everything in layer after layer of super-complex modal trains.
2. Buried under redirection and required security clearances is the information that the patterns of tracks isn't random, with railroad gates monitoring other trains and switching tracks to create a massive Babbage-equivalent computer of unknown usage improving itself rapidly as it grows bigger.
Needless to say, there will be a link between this and the CotBG with this being a "piece" of the Broken God.
What do you guys think?