so I read this book at latest in the late nineties, but it's about a giant strand of alien super metal that is found on an unclaimed planet. its discovery sets off a kind of galactic gold rush between disparate alien civilizations who would all have different essential uses for this fantastic material, including a species of intelligent sentient tentacled dolphins in space. it is super light but strong and malleable. one civilization wants to use it as a cheap space elevator, another wants to use it as a kind of atmospheric trebuchet, another wants to use it for armor or weapons. it is basically a towering macguffin that reaches into the atmosphere. I don't remember who wins or who made it, but i'm stoked to re-find out.
I think this might be 'Spinneret' by Timothy Zahn. In this book earth is setting up their first interstellar colony. They find a mountain sized factory hidden there that creates long strong cables that it ejects into orbit. The process of creating these cables leaches metals from the planets crust. https://en.wikipedia.org/wiki/Spinneret_(novel)