Joseph Beuys - The End of the Twentieth Century, 1983-5. Basalt, clay and felt
From the Tate Gallery, London:

A major theme in Beuys’s work was renewal. This sculpture developed out of his environmental concerns, particularly a plan to plant 7,000 oaks in the city of Kassel, Germany. Next to each newly planted tree would be placed blocks of basalt rock. Here, the basalt itself becomes a symbol of potential growth. A cone has been cut out of each rock, allowing the cavity to be lined with clay and felt. Embedded in dead matter, these materials suggest the possibility of new life emerging at the end of a dark century.

Joseph BeuysThe End of the Twentieth Century, 1983-5. Basalt, clay and felt

From the Tate Gallery, London:

A major theme in Beuys’s work was renewal. This sculpture developed out of his environmental concerns, particularly a plan to plant 7,000 oaks in the city of Kassel, Germany. Next to each newly planted tree would be placed blocks of basalt rock. Here, the basalt itself becomes a symbol of potential growth. A cone has been cut out of each rock, allowing the cavity to be lined with clay and felt. Embedded in dead matter, these materials suggest the possibility of new life emerging at the end of a dark century.

Jeff Koons - Bourgeois Bust - Jeff and Ilona, 1991. White marble
From the Tate Gallery, London:

'Bourgeois Bust' was originally created for the 'Made in Heaven' exhibition, in which Jeff Koons explored the concept of love in relation to his own marriage to porn star Ilona Staller. Represented as a marble portrait bust, the couple are depicted within a traditional Baroque style that drew its inspiration from antique classical sculpture. With her plaited hair and string of pearls, Staller appears like Venus, the Greek goddess of love. Declaring sensationally “We’ve become God”, their spiritual and physical union seemingly elevates the pair to a higher realm of idealised existence and ecstasy.

Jeff KoonsBourgeois Bust - Jeff and Ilona, 1991. White marble

From the Tate Gallery, London:

'Bourgeois Bust' was originally created for the 'Made in Heaven' exhibition, in which Jeff Koons explored the concept of love in relation to his own marriage to porn star Ilona Staller. Represented as a marble portrait bust, the couple are depicted within a traditional Baroque style that drew its inspiration from antique classical sculpture. With her plaited hair and string of pearls, Staller appears like Venus, the Greek goddess of love. Declaring sensationally “We’ve become God”, their spiritual and physical union seemingly elevates the pair to a higher realm of idealised existence and ecstasy.

Robert TherrienNo Title (Table and Four Chairs), 2003. Mixed media 

From the Tate Gallery, London:

No Title (Table and Four Chairs) invites the viewer to walk around and underneath it, experiencing the sculpture physically and additionally transforming the viewer’s perception of the exhibition space. Despite their physical quality, however, the roots of Therrien’s table and chair works lie in photography. Intrigued by the view beneath his kitchen table, the artist took a series of black and white photographs from the perspective of his floor. No Title (Table and Four Chairs), as well as the preceding sculptures, is an attempt to create the same dramatic viewpoint as in the photographs.