The artist’s hand.
by Self-Portrait of the Artist
The artist’s hand has been his earliest object of self-portrayal, ever since the (probable?) dawn of art in the paleolithic.
That was during the last ‘ice age’ — but I reckon Adolph Friedrich Erdmann von Menzel did not know this, as he set about painting the Artist’s hand with ice cube in 1864.
Sixteen years earlier he had experimented on the same subject with his Right hand drawn with the left hand; twenty-two years later he would paint his own foot.