I imagine a biological creature, let's call it 'Marco' for now.

Marco can vomit living slimes that survive by attaching to the ground and by doing photosynthesis, at first soft can be shaped and modeled before it hardens permanently.

When hardened it can fuse with other slimes vomited to form various structures. The slimes are made of living mass that can be eaten again by Marco but are poisonous to anyone else.

Marco has managed to create a living underground bunker to defend from other creatures, the bunker looks something like this, outer bio-structure with underground space. Picture depcits the Zerg, an alien species from the game Starcraft, who build living structures from their larvae

My question is, can a creature like Marco evolve naturally without being created by gods or mad scientists?

  • 2
    $\begingroup$ Welcome to WorldBuilding Ekaen! Interesting question. If you have a moent please take the tour and visit the help center to learn more about the site. Have fun! $\endgroup$
    – Secespitus
    Commented Mar 17, 2018 at 12:52
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    $\begingroup$ Where is the picture from? Is it your own art? $\endgroup$
    – Willk
    Commented Mar 17, 2018 at 15:54
  • $\begingroup$ it's just a picture i found when searching for alien structures, reminds me of some really old browser game $\endgroup$
    – Ekaen
    Commented Mar 17, 2018 at 16:25
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    $\begingroup$ Not that much different from terrestrial bees, except for the part about being poisonous to everything else. Bees collect nectar, pollen, &c from photosynthetic creatures - plants - then turn it into various "slimes" that become beeswax, honey, royal jelly and so on. They then use the beeswax to build parts of their homes (which can be underground), and to store food that can be eaten later. $\endgroup$
    – jamesqf
    Commented Mar 17, 2018 at 17:48
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    $\begingroup$ The image looks like a Zerg structure from Starcraft 2. Possibly one that hasn't finished hatching yet. $\endgroup$
    – Nolonar
    Commented Mar 17, 2018 at 19:18

2 Answers 2


Marco is a farmer.

The placement of slimes for later retrieval once they have bulked up their biomass photosynthetically seems like a kind of farming to me.

I am reminded of leaf cutter ants. https://en.wikipedia.org/wiki/Leafcutter_ant

The ants cultivate fungi, not photosynthetic organisms. But their colony is made of this fungal matter, just as you want Marco to build his fort out of his exosymbiotic slimes. Here is a leaf cutter ant nest structure made of fungus, leaves and ant secretions.

leafcutter ant colony http://www.leafcuttingants.com/coloniesforsale.html

As regards symbiotic photosynthetic organisms, lots of creatures have these (sponges, corals, lichens) but all that I am aware of keep the symbionts - endosymbionts - safe within their own tissues. The ants have exosymbiotic fungi outside their tissues but they are guarded in the nest.

There are definitely symbiotic relationships between ants and plants, and the plants even make structures to help the ants, but it is not the same as the leaf cutter ants (or Marco) building new structures out of the exosymbiotic organism and associated material.

I think the problem with photosynthetic exosymbionts as you propose (the slimes) is they are not inside Marco and they must be in the sun, and so would be susceptible to being eaten by other things when Marco is away.

You knew this too and so made the slimes toxic to all but Marco - that could work. But what about conspecifics of Marco's species? Presumably there are others. Marco's cousin could show up and eat Marco's slimes while he was elsewhere. Maybe the Marco creatures have territories they defend from conspecifics - that would make sense.

I like this idea. The idea of a territory used to farm photosynthetic exosymbionts makes sense. It is so sensible I feel like it must happen but I cannot think of an example. Still thinking...

As regards building things out of your exosymbionts, why not? The leaf cutter ants do. You could build out of a tough, woody, lichen-like exosymbiont / slime.


What you propose is a variant of what already exists in some cases: some animals eat fruits of plants. They poop the seed, the seeds grow and make a new plant (which makes photosynthesis) and produces new fruits which can be eaten by the same kind of animals.

Since you want to enhance the specificity of the relation, you can go for a symbiotic relation between Marco and another organism: the organism recognizes Marco's antigen and vice-versa ensuring mutual tolerance.


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