Our pilgrimage is now a milling horde, having amassed all the vertebrates, together with their primitive chordate cousins, amphioxus and the sea squirts. It comes as quite a surprise that the next pilgrims to join us, our closest relatives among the invertebrates, include those strange creatures—we shall soon refer to them as ‘Martians’—the starfish, sea urchins, brittle stars and sea cucumbers.
