Very rare resin cube, designed by Enzo Mari in 1959 and made by Danese.  The cube is made of transparent polyester resin and inside there is a black sphere - there are some little chips.  "Attributing a specific volume to a comparison modulus allows the perception of its consistency to be improved. The relationship is even more evident and significant the more the two elements (or at least one) are simple and correlated. The maximum correlation is obtained by incorporating one element in the other, thus establishing a contained-container relationship." Enzo Mari in 'Funzione della ricerca estetica' (The function of aesthetic research), Milan 1970.