n. 轮藻

[ noun ]
any of various submerged aquatic algae of the genus Chara having nodes with whorled filamentlike branches; usually encrusted with calcium carbonate deposits
<noun.animal>

Stonewort \Stone"wort`\, n. (Bot.)
Any plant of the genus Chara; -- so called because they are
often incrusted with carbonate of lime. See {Chara}.