Jumping from eyes-close-to-brains-in-lower-animals to brains themselves, I recall a little gem of a puzzle published by John de Cuevas in October 1994, whose solution read:

     The juvenile sea squirt wanders through the sea
      searching for a suitable rock or hunk of coral
              to cling to and make its home for life

               When it finds its spot and takes root
                  it doesn’t need its brain any more
                                       so it eats it

  
                     It’s rather like getting tenure

-- Daniel Dennett, Consciousness