Their website says:
"Volcanic glass, procured by remelting Etna’s rocks, has been mouth-blown into unique vessels or cast into box-like structures that purposefully allude to the illegal dwellings and assorted buildings that have developed at the foot of the volcano. Drawing on their own vocabulary, these solitary glass boxes and mysterious black buildings have been finished with such archetypal Formafantasma detailing as cotton ribbons and Murano glass plaques. By returning the rocks to their original molten state Formafantasma are reversing the natural timeline of the material and forcing a dialogue between the natural and manmade."
Future relics. WOW.