noun
periphyton
Technical term in ecology and limnology for the community of microorganisms, algae, and small animals attached to submerged surfaces in water.
河川の石の表面には付着生物が多く見られる。
Periphyton is often found on the surfaces of stones in rivers.
Compound of 付着 (fuchaku, 'attachment') + 生物 (seibutsu, 'organism').