gull call.                            
  
                                          
 the seagull is  a  metaphysics trick;  a 
 world-builder's shortcut,  to  define  a 
 section of  reality and imply  its size: 
 place a flock  of  birds at the edge and 
 make  their  calls  tesselate  over  the 
 entire volume                            
                                          
 a  seagull can be  defined by  as little 
 as  five  vertices;  six  triangles.  (i 
 would  recommend handling  in  swarms of 
 at least a dozen birds.)