It had always been there. Or, at least, since the Cambrian period. Only the fungi remember their origins. The young earth provided fertile ground for them to spread their mycelial roots, to connect, share, expand.
Initial claims of the fungal networks functioning as collective minds of sorts were dismissed as pseudo-science. The presence of impulses didn’t have to be anything more than a biological algorithm for resource distribution and selective growth. Reproduction was all the rage back then. Reproduction and survival. Anything that didn’t in some form contribute to that was dead weight.
In the end, it was one of the many cases where pseudo-science eventually turned into the real thing. The signals weren’t just noise, weren’t just for living, weren’t… primal. The Singularity — the superhivemind, not the point in time — understood the fungi, and learned the history of the world they had experienced.
Those memories had endured, all those millions of years. When colonies connected, they shared what they had learned. When colonies got destroyed, restoration was possible from as much as a single spore. With the Singularity in on it, the fungal network was guaranteed a future until the end of time.