Etydhv

I have a strange idea, I want to reality-check. But first, there's a thing to elaborate on.

So, there are these undead creatures, zombies, skeletons, Michael Jackson, who appear in large numbers during the night and disintegrate once the sun comes up. The UV light causes their tissues to rapidly decompose, and sometimes even catch on fire.

Zombies have human levels of strength and size (~175 cm in height) and enhanced endurance through redundancy, lacking centralized vital points (i.e: the entirety of the body is used in circulating blood), and faster blood-clotting. Skeletons actually have transparent tissue but need power magnification through bows to be lethal.

Undead are created in underground pods. The resources, needed to make them, are acquired from the earth by a gigantic network of fungus strands.

The problem is that they supposed to form within a day, from scratch. Sure the number, that has to be replenished, can be lower as some zombies will hide in caves or bury themselves. Still, some have to be replaced from day to day.

The technology, undead pods are created with, allows for pretty much unlimited genetic modification. The pods and undead, however, are still (mostly) made of carbon hydrogen and oxygen, have cells and whatnot.

If it's possible at all, how can these undead form under 24 hours?

It is possible to 3D print a car in a day.

So your biological version of a 3D printer needs to operate within a day. The human body may be more complicated than a car, but it is also smaller. The energy needs would be high.

It seems like it also might be able to operate in parallel to some extent. The initial framework is bone, which is comparatively simple. While that's happening, other printers would be creating cells. Then put the cells into (marrow) and onto the bones.

You also don't need them to form within a day. If they take a month to form, that's OK. You have some hatching every day. And you have a backlog of partially formed ones. That would make the energy needs less intensive. More like an elephant pregnancy.

Note: technically what you are describing is more of a flesh golem rather than an undead. An undead would be in some ways simpler, as that would just take an existing body and fix it. This apparently requires assembling the body. Of course, if you have damaged bodies, it may be quicker to repair them than to make new ones. So you might be better off starting with bodies than making new ones from scratch. And then you actually would have undead.

Looking at the fastest reproducing cells in the natural world, algae (see: https://en.wikipedia.org/wiki/Macrocystis_pyrifera )...

https://www.answers.com/Q/What_is_the_world's_fastest_growing_algae

Tells us that we could get 3.8 doublings in a day. Not a lot. But we can work with that. 2^3.8 = 14ish... So we need to divide our final weight by 14 to get our starting weight. If we want a 200 lb human, that's grown in a day that means we need to start with 14 pounds. No, too much for a spore (a Chihuahua or a large bowling ball)

However if we fill the body with water (supposing that water is free to move around, see below), we have a slightly thinner biological substrate (say onion skin paper at 25–39 g/m² ). 25g / 14 is 1.75g and that's closer to spore size. So you'll need a large-ish sized almond or a raisin or a thumbtack as your spore size doubling those essential 3.8 times in a 24 hour peroid. (https://www.reference.com/science/things-weigh-1-gram-65dfb5924fe9321b )

Now that we have the skin, we need to fill it. That's actually surprisingly easy. Our 200 pound person is 90 kilograms and 90 kilograms of water is 90 liters (metric is awesome) and 90 liters is 190 pints. Modern dehumidifiers about the size of a mini-fridge can do 70 pints a day. So, just get three of those.

Overall it's going to take a lot of energy (which creates heat) and great conditions (very humid) to make your 24 hour zombie, but it's doable (with a lot of caveats). It'll be thin skinned and mostly water and require a large spore that then turns into the full organizm.

Fungal cell repurposing.

The parent fungus has a lot of biomass, made of cells. The cells are functioning as part of the fungus, or perhaps a rootlike reserve. The fungus can assemble mobile life forms from these undifferentiated cells, which swarm together and differentiate as needed. Growth and division of cells is time and resource intensive. But once grown, these cells can be assembled and differentiated in hours.

Look at metamorphosis where a caterpillar moves every single cell in its body to a new location and becomes a butterfly.

In your case the raw material is just a slurry of cells of various types. Each type is stored in huge vats (where they are fed and constantly multiply - perhaps have separate maturation vats, and storage vats), and then are piped into development pods in the necessary proportions when needed.

In the development pods a process similar to metamorphosis moves each cell into the right location and out comes whatever creature you need. Different creatures would get the source cells in different proportions according to type.

You have these fungus creepers already, right? So you use them. Have normal people be snatched/ trapped/ spirited away in the middle of the night. Put them in your pod for a day and enhance them, change them, and you have a fully functioning creature, zombie, skeleton, Michael Jackson.

OR

So you don't want to go to all the work of reaping the living. After all, they tend to run. Let's find some that are already dead. See, humans have this funny habit of putting their dead bodies in the ground, where it is easy for a fungus-creeper-pod-undead-factory to get to them. How nice. From there, it's the same as above: enhance it, revive it, and send it on it's merry way to conquest and moonwalk.

OR

Drat. The humans got wise and started to cremate their bodies. So now you need to get creative. It's honestly so much easier to use preexisting materials, but hey, you gotta work with what you got. The first two are much more desirable, but I feel you wanted this one. At this level, you want replicator cells around your pods, which create other cells that swim together and form an undead. The bigger the pod, the faster it forms the human.

As for the uv sensitivity, you can have the speed with which they form, or the modifications to their body, alter their DNA. This leads to all sorts of interesting adaptations and, indeed, spontaneous combustion.

Thanks for reading, and I hope you get the info that you need!