M. C. Escher made a lifetime study of patterns and tilings, often, as here, with strange symmetries between figure and ground (starfish and seashells -- both bivalves and gastropods). Escher was clearly delighted that a 5-symmetrical animal existed, and determined to overcome the mathematical impossibility of tiling a plane with fivefold symmetry. So the starfish fit into a rectangular pattern, and they form junctions at which either three or four animals touch arms. It is typical of Escher's careful observation that the starfish have accurate anatomical details. No artist more perfectly exemplifies the interplay of art and science. For me, there is a parallel but subtly different interplay of artifice and nature; from that perspective, Escher's work is skewed heavily towards artifice, and indeed he also depicts impossible situations such as endless staircases. But one has to admire his beautifully constructed "periodic drawings".