{HEAD ~ The algal turf} naturally has {TAIL ~ a surface} comprising the cell walls of the algae 
naturally has
{ HEAD ~ The algal turf } naturally has { TAIL ~ a surface } comprising the cell walls of the algae
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH