Tweet this page Like this page Email this page Share this page Home» Resources » Identification » Identification of algae » Freshwater algae » How to identify algae » Identification guide » Filamentous Algae are filamentous (either cells joined end-to-end or comprised of long tubes without cell walls, may be branched or unbranched, or like a net) 2. Please choose size of individual filaments. Individual filaments are microscopic (magnification is needed to see any detail) Individual filaments are macroscopic and easily discerned with the naked eye; could be confused with pond weed or fine grass