Zoosporangium of Halophytophthora tartarea. This is one of the eukaryotic marine mycelial decomposers that were until recently considered fungi, but are known to have evolved the mycelial-decomposition ecostrategy independently from the members of the Kingdom Fungi. The halophytophthoras are more closely related to diatoms than they are to fungi. The sporangium (about 50 microns in diameter) contains a clear plug at its mouth. The plug is expelled at maturity, and the zoospores (the shiny beads within the sporangium, about 12x5 microns) swim away. The zoospores are biflagellate and similar morphologically to bactivorous flagellates of marine nanoplankton. Photo from old ASLO slide collection; taken by S. Newell; background information by S. Newell; scanned by K.L. Schulz.