This is the same microalga of standing-decaying smooth-cordgrass blades, as seen in the previous link (Pseudendoclonium submarinum). This preparation, however, has been fluorochromed with calcofluor, which has adhered to the algal cell walls, and caused them to fluoresce blue-white when excited with 350-380-nm UV light. Thus, in this image the whole of each cell of the alga (about 3-5 µm across) can be seen, rather than just the red-fluorescing clorophyll-containing portion as in the previous link. Calcofluor is also a fluorochrome for fungal hyphae; a hypha can be seen in this image (the filament running diagonally between the two large algal colonies). Most of the fungal hyphae of the decaying-leaf system are not on the surface with the algae -- they're inside. Is this partially because the fungal hyphae are not good at defending themselves against predation (by protozoa?; by bacteria?; by viruses?). See Newell, 1993, Adv Microb Ecol 13:301-326; Newell & Porter, 2000, pp.159-185, in Weinstein & Kreeger, Concepts and Controversies in Tidal Marsh Ecology, Kluwer.