A "new" form of carbon stronger and stiffer than any known material. Also known as linear acetylenic carbon, carbyne is an indefinitely long chain of carbon atoms that are joined together by sequential double bonds or alternating single and triple bonds (a polyyne). Detected reportedly in asteroids, and synthesized only in vanishingly minute amounts in a lab. Only a single molecule thick, meaning that, for a given mass of carbyne, the surface area thereof is relatively immense.
"The researchers found that carbyne is massively strong (6.0–7.5×107N∙m/kg, vs. 4.7–5.5×107 N∙m/ kg for graphene), very high tensile stiffness (it’s almost impossible to stretch), fairly chemically stable, and yet surprisingly flexible."