These macroalgae (large algae that resemble higher plants at a quick glance) live on the lake bottom, and are known as stoneworts. Look at how beautiful they are.
This one is called Chara vulgaris, or common musk grass, as it has a strong, skunky odor when lifted out of the lake. I cut through the 'stem' of one to show the beautiful whorls on which the male and female reproductive structures (spots/dots) are located.
Their whorls glitter like gold in sunny waters. They are eaten by waterfowl, and provide excellent fish and invertebrate habitat, providing both cover and food for their immature offspring.
They are said to be excellent in slowing the movement and suspension of sediments, acting as a stabilizer according to Through the Looking Glass: A Field Guide to Aquatic Plants.