To the naked eye, this looks like plastic and human-made. Yet, upon closer look, there are signs that it is not so mundane.
In this video, for instance, you can see silver-ish worm-like structures appear to emerge from the structure and then become coated in a black 'goo,' thereby becoming par of the larger structure. It is also not uniform in any way, and you can also see pieces of the same kind of structure appear to emerge in smaller chunks nearby. Additionally, when sprayed with a strong antimicrobial, the black 'goo' dissolves, leaving silver-ish filaments behind (see 'black-mesh/grid" ). I asked the inspectors and contractors who consulted with us if they knew what it was. While they (like I) initially assumed it was some (plastic) construction or roofing material, a closer look left them unsure, too. They told me that it was very odd that the black 'goo' would dissolve in antimicrobial solution (as plastic apparently shouldn't do so?. Other signs that something different is going on: seemingly identical structures have been documented embedded in human skin and also coming off of domestic animals.
This continues to be one of the most perplexing structures.