Chara is a type of algae which is low-growing and appears like an aquatic plant with no true roots.  The algae has cylindrical whorled branches with 6-16 branchlets coming off of each node.  This plant is also commonly referred to as Muskweed due to the musky odor which it can produce

While it is a type of algae, Chara is very beneficial in aquatic systems as long as it does not become overgrown.  Chara proves to be an excellent source of oxygen in the water as well as a shelter and food sources for fish, macro-invertebrates, and micro-invertebrates.