Utterly Mad

Shroomsteel
Mohs hardness: 0,7
Electric resistance: None
Mass: 0,5kg/liter

Shroomsteel is a mysterious alloy produced by the Truffles.
It is extremely light and soft. It is almost 3 times softer than lead. It is a superconductor, which is why the Truffles use it to make electronical devices, and to trade with other civilizations.
It is made with mysterious technology that no other race has the knowledge of.
It is extremely reflective, reflecting even better than the best mirrors made by the Humans.

So, laser defense and conduction? Seems good to me.

I feel like this material alright but I have a few caveats. I feel like it should be extremely rare in the galaxy at large and obtaining Shroomsteel should be a quest reward someone has to work hard for. Also since only the delicious mushroom men can make it, it would only make sense that they would be the only one's to know how to fashion it into anything useful unless someone was taught the process.

The Truffles taught the humans how to work it, but not the process of making it. (secret: Shroomsteel is basically truffle remains mixed with copper. It is their version of burial.)

I feel like this material alright but I have a few caveats. I feel like it should be extremely rare in the galaxy at large and obtaining Shroomsteel should be a quest reward someone has to work hard for. Also since only the delicious mushroom men can make it, it would only make sense that they would be the only one's to know how to fashion it into anything useful unless someone was taught the process.

Why would Shroomsteel be so rare? I can't see it being used for anything else than reflective surfaces and electronic circuitry.

Because it only has one production source in the entire galaxy and if it makes such a great conductor everyone and their mothers would be buying it up constantly? Maybe I'm missing something here.

One production source =! Rare.
They are only supplying it to humans. They don't even use that much of it themselves.