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I am designing a genus of eusocial, high-temperature, extraterrestrials from the planet 61 Virginis b. They are based on tungsten chloride and use sodium chloride as a solvent. This species has sessile queens that can grow up to 1,000 feet. This is facilitated by the fact that upon maturity to stage, they mostly consist of their shells and all fleshy bits have been reduced to branching tendrils that creep along the inside of the shell making the internal cavity.

The problem is this planet has a very high temperature, around 800 Kelvin, which is perfect as the triple point of sodium chloride, but bad for tall structures, even ones made from tungsten. To add insult to injury the gravity of the planet is five times that of Earth, making tall structures even more unfavorable. The shell needs to be hollow because the harams of male workers retreat into the shell and it's the only way the males get access to reproduction. The hollowed cavity is also the only way the queens can have their harems regulate their body temperature, through the closing and opening of pores for ventilation.

So bearing all this in mind what shape should this shell be so that it can grow up to 1,000 feet without it collapsing due to gravity or the heat making the tungsten compounds it consists structurally unsound?

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  • $\begingroup$ Do your queens need to be tall? If yes, why? If not, they can be like a mangrove forest, spread horizontally. $\endgroup$
    – Vesper
    Jul 26, 2023 at 16:03
  • $\begingroup$ @Vesper yeah the need to be tall, the main reason evolutionarily is primarily to increase how large the harems can be while decreasing how much land is taken up by the queen’s body. The secondary reason is it serves as a good lookout point for the messenger caste. $\endgroup$
    – Amoeba
    Jul 26, 2023 at 16:19
  • $\begingroup$ A thousand feet long, or tall? If the former, how tall. If the latter, how long/wide? These matter for architecture. $\endgroup$ Aug 3, 2023 at 17:20

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We're going to have to assume that the queen can't roll over. I can't imagine any structure that tall that could be laid on its side.

With that restriction, your shell would be a fractal agglomeration of catenary curves.

Gateway Arch, an archetypical catenary curve

This shape is the shape that best resists gravity. A flying buttress is usually designed as half of one of these. An organic process could readily adjust the shape in order to keep internal supports at the right angle to fight whatever pressure is applied, but this is the shape that they would wind up using, at numerous scales.

recursive arches

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I think your sessile Queens shell should be cone-shaped. A cone is stable in high gravity because the wide base spreads out the weight and the narrow top has less weight to support.

Because the cone should be hollow in your plot, the shell can be supported by vertical ridges on the outside, to give it extra strength. Additionally, it should be thicker at the bottom than at the top to be able to handle gravity (i.e., the cross-section of the shell is thicker at the bottom).

For the material, tungsten carbide might be a good choice. It melts at 2,785–2,830 Celcius, it has a high Young Modulus (higher than steel), and hell it is even used to make armor-piercing ammunition when depleted Uranium is not available.

So my vote goes to a cone-shaped shell made out of tungsten carbide!

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I have searched for engineering documents on the effect of temperature to strength of Tungsten. All the charts I found starts from over 1000K. However around 800K Tungsten becomes ductile, unsuitable for large constructions. However, I found the following chart showing there are alloys of Tungsten that holds their strength at much higher temperatures. Yield strength of Tungsten alloys

I am certain in a Darvinean hellscape like yours, life will find similar alloys that will allow them to construct incredibly intricate shells that create a suitable environment like you have described.

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