Do you know which is the word's lowest density solid ?

Do you know which is the word's lowest density solid ?

The word's lowest density or the lightest solid material is Averogel which is composed of about 99.98% air by volume. It is usually composed of sillica or carbon compounds.it is a synthetic material that is dry, translucent, porous and solid framework of a gel. in general, aerogels are pretty frangle. Due to its appearance and ultra-lightweight,it is also named 'frozen smoke'