Sometimes art pieces are shattered into pieces of art, like most of the Parthenon statues, either shot or fallen to the ground after goofy attempts of removal. For preservation, or pillage?
Other times, pieces of arts are made out of single pieces, as no time or money were sufficient to complete them. Like the Great Door of the temple of Apollo on Naxos, surrounded by nothing but a few stones.
Nature might be the artist on man made pieces abandoned on the sea bed… like this broken metal barrel covered with algae and anemones
or nature might be the inspiration for the ideal proportions of these Kuroi at the Archeological Museum of Athens
or, once more, nature might create art from scratch, like Araucaria heterophylla trees. Despite that art is a “highly diverse range of human activities” and nature is not human, the geometry of these plants is artistic.
Art pieces and pieces of art usually find their ways to museum, however split they are. Also museums can be pieces of art, like the Acropolis Museum of Athens.