The lightest material ever made was invented in 2011. It is made out of a microscopic micro-lattice of hollow tubes – a criss-cross diagonal pattern with open spaces between the tubes. The researchers say the material is 100 times lighter than Styrofoam and is very strong. The material is low density: it has a density of 0.9 milligrams per cubic centimetre. Silica aerogels, the world's lightest "solid" materials, are only as low as 1.0 mg per cubic cm. The metallic micro-lattices are 99.99% air and only 0.01% solid. The metal used is nickel.