providing a growing surface in said water to which said {HEAD ~ algal spores} form {TAIL ~ an attachment} 
form
providing a growing surface in said water to which said { HEAD ~ algal spores } form { TAIL ~ an attachment }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL