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