We love Giuseppe Penones bronze sculptures of hands gripping trees. The Italian sculptor installed a few of these hands onto small trees and in the intervening years, the trees have grown, developing the sculpture further.
The hands appear now to be squeezing the trees, the bronze fingers stretching the bark into ridges. The results are beautiful, but its hard not to wonder what effect the metal will have on the trees in the long run. Motivated by environmental concerns like this, one artist created a response piece, sculpting the hand out of burlap so it will dissolve as the tree grows.