5 min read

Building Beyond: Mycorrhizal Networking

I had a longer joke, but there’s not mush room for it here.

Building Beyond is an ongoing series of conversations about how much fun worldbuilding can be. Building a world doesn’t have to be hard or scary. Let’s give it a try, together.


City planners in this civilization rely on fungus to help them do their jobs.


Author of the acclaimed web serial Into the Mire, Casey Lucas is a writer and game developer based in New Zealand. She was the recipient of the 2020 Sir Julius Vogel Award for Best Short Story, NZ's highest honour in short form fantasy fiction.

Gailey: How does the fungus help the city planners to plan the cities?

First off - thanks so much for coming to our open day. I always wonder about reporter types, but your questions have been so unbiased thus far. We do appreciate it.

It starts, like many things do, with goo. With a slime mold, to be exact. Mycelial networks are expensive and time-consuming to install, so after a couple memorable failures, slime modelling became the industry standard. Nobody wants a repeat of the flood of '28, after all.

Our engineers sculpt clever printed-stone models of the site's bedrock, then layer it with real-world soil samples, water features, and an exact mirror of the hazards of the local topography. Then the network can begin to grow.

Slime molds, without fail, will discover the most efficient route between two points. If we plant our samples at sites which mirror the real-world locations with the deepest mycelia, we now know the ideal routes for laying our "cables." Carbon exchange, information sharing, traffic management, surveillance - slime's been at this since the NSA were primordial sludge.

Gailey: Are there drawbacks to fungal involvement in city planning?

Apart from the fact that some varieties take so damn long to grow? A few. Inevitably. It's enviable technology, so as with anything people covet, the real issues spring from defending it. People don't just want to steal the fungus, they want to steal what it knows. While we have our methods, you can't just throw up a firewall around fungus.

The mycorrhiza - the little dangly bits that latch onto the trees, the buildings, the fibre optic, what have you - don't segregate or vault their knowledge. Any Stemhead determined enough could in theory dip their toe into the sum of our network's distributed knowledge. But only in theory. Because like I said, we've got our methods.

Is it really fair to blame the fungus for the Stemheads? I don't think so. Hippies have been doing shrooms in the woods since Adam was a cowboy. All their weird little tricks, the dust-huffing, the mushroom-ink tattoos, the spore transfusions, it's all more likely to put them in the hospital than grant them access to our data. Honestly, I feel kinda bad for 'em.

Gailey: How are the daily lives of citizens impacted by the fungus?

This is like asking the Romans if their daily lives were impacted by hot baths and sewers. Most folks don't think about the fungus, but they'd miss it if they had to get from A to B without it.

A living, breathing road grid that adapts instantaneously to the flow of traffic? Emergency alarms that can summon fire and ambulance to exact addresses at the speed of subterranean thought? Fool-proof sporeprint tracking of undesirables down to the footprint level? Every blade of grass in this city could trip an alarm if we needed it to. People used to use cameras for this crap.

It's the Stemheads people are really afraid of. The weird, shivering junkie ones. The backwoods hippie ones with their weird, primitive religions. Or the worst ones of all, the militant ones, the assholes who are intent on dragging us back into the dark ages.

Our roads can divert floodwaters before they reach our thresholds. We haven't had a missing kid in decades - our mycorrhiza can hunt them down before any harm comes to them. Our power grid diverts energy only to where it's needed most.

For every mewling snowflake who whines about the roads having eyes, there's a hundred people who wouldn't trade it for the world.

It's safe here. It's the safest humans have ever been.


Arkady Martine is a speculative fiction writer and, as Dr. AnnaLinden Weller, a historian of the Byzantine Empire and a city planner. Under both names she writes about border politics, narrative and rhetoric, risk communication, and the edges of the world. She is currently a policy advisor for the New Mexico Energy, Minerals, and Natural Resources Department, where she works on climate change mitigation, energy grid modernization, and resiliency planning. Her debut novel, A Memory Called Empire, won the 2020 Hugo Award for Best Novel. Arkady grew up in New York City, and after some time in Turkey, Canada, Sweden, and Baltimore, lives in New Mexico with her wife, the author Vivian Shaw. Find Arkady online at arkadymartine.net or on Twitter as @ArkadyMartine.

Gailey: How does the fungus help the city planners to plan the cities?

Put a little agar agar at every hypothetical bus hub on your new transit map and let a slime mold do the modeling for you: there grows the quickest, simplest network lines, spun out in fungal strings. The trick is to build like a slime mold. It creates efficiencies.

(To convince a city council that a slime mold is quite clever, perhaps cleverer than they are, and secure the budget to build like a slime mold? That’s not just a trick: that’s a campaign. The slime mold helped. By then, the planners knew it quite well; had begun to dream its slow and slick reaching dreams. Wore it like tattoos, glowing, moving – and what aspiring planner would dare to come to work without their own creeping, enveloping net of light?)

Efficiencies … spread.

Gailey: Are there drawbacks to fungal involvement in city planning? How are the daily lives of citizens impacted by the fungus?

In other cities, there are auteurs of architecture, spectacular civic design, ugly buildings – in other cities, there are apartments where each room is both of a different size and has perfect right angles at every corner – in other cities, there are differences in neighborhoods (this one with poor sewerage, this one with better schools, this one with restaurants that serve cuisines half the citizens have never imagined) – in other cities, there are open spaces both smaller and larger than necessary for optimal human exercise and social interaction –

In other cities, no one touches wrist to wrist, feels an echo of another person’s breath and rushing blood, a taste of other lives meeting in glowing lines. In other cities, the story goes, everyone is as lonely as children are, before they begin to plan.


Both of these possibilities are just beginnings. Casey's city is full of salesmen, eager to turn ideas into cash. Arkady's city is a stunning examination of connection and innovation.

What can your fungus engineer? How might it change the way we live?

Do whatever you want with these questions. You can write something down in the comments or on social media or in a notebook nobody will ever see. You can draw or paint or sit down a friend and talk their ear off about your ideas. You can stare at the horizon and imagine, letting the infinite landscape of your mind unfold just a little farther than it did yesterday. No matter what you do, take pride in the knowledge that you’re creating something that has never existed before. You’re building a little corner of a whole new world.

That’s amazing.


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In the meantime, care for yourself and the people around you. Believe that the world can be better than it is now. Never give up.

—Gailey