Submerged Plants. Stonewort (Giant Green Algae, Chara, Nitella). Other names given to stonewort are 'giant green algae' and 'muskgrass'. (Norwegian: Kransalgen grønnkrans).
Stonewort Botany: any plantlike green algae of the class Charophyceae, especially those of the genus Chara, characterized by a jointed filamentous or thalloid body, often encrusted with calcium carbonate.