Rustilium

Rustilium is a shiny metallic compound of Helium-3, gold, and cellulose of tree wood. It has become the basic building material of spaceships and space colonies because of it's unique properties. It is 25 times stronger than steel, lighter than aerogel, and edible by humans. The material was discovered in the year 2134 by Sir Albert Shearwater while trying to develop a sustainable substitute for shaving cream.