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?