Other name: Stonewort (usually refers to Nittella spp.)
Let’s get it out of the way from the start: Chara is not a grass. Calling it a grass is just plain dumb; it looks and behaves nothing like a grass, so I’m going to call it Chara. The musk part makes much more sense because Chara does indeed have a musky smell when damaged or crushed. The next, and more important thing to get out of the way is that Chara is not a vascular plant, and produces no flowers or seeds. It is a macro alga like kelp, but is not closely related. It, and another common algae, Nitella, is one of the reasons biologists use the term macrophytes to describe aquatic vegetation, and avoid the term plant. It seems rather silly since “phyte” means plant.
Anyway, Chara is a pretty interesting algae. Not only is the alga large, it also has comparatively giant cells. What might be called leaves are made of one single, extremely long cell easily visible to the naked eye. Chara often has a gritty feel to it; this is caused by lime that encrusts the alga. Chara is an important food for waterfowl when they produce the spore-like oogonium, which many ducks relish.