This tiling and Nautilus are dual tilings generated by non-PV morphisms. As such they are the first step in a generalisation of the work of G. Rauzy, P. Arnoux, S. Ito and others for PV substitution rules. The work that developed out of G. Rauzy’s seminal paper [Rau82] .
The inflation factor for this substitution rule is either of the expanding roots of:
$x^{4}-x+1 = 0$. Note that this it is related to R. Kenyon’s example
Kenyon 2 that is shown on his homepage: http://www.math.brown.edu/~rkenyon/gallery/gallery.html and has
inflation factor satisfying $x^{4}-x+1 = 0$.
Conch (Volume Hierarchic) is a volume hierarchic, version of this substitution rule with fractal bounded tiles.
 
    
	
    
     
    
    
	
    
	
    
	
    
  [Rau82]
  Rauzy, G
  Nombres algébriques et substitutions (French) [Algebraic numbers and substitutions]
  
    Bull. Soc. Math. France
  
  1982,
   110, 2,
   pp. 147-178,
  
    
      
        MR0667748