Hyphae - threadlike filaments of branching cells that make up the bodies of multicellular fungi. Gymnosperm - group of vascular plants that develop seeds without a protective outer covering; they do not produce flowers or fruit. Flagellum - a tail-like structure found on bacteria and select protists which helps them to move. Volvox - a freshwater, chlorophyll-containing green alga, that occurs in ball-shaped colonies.