This zoosporangium of Halophytophthora exoprolifera has just an instant earlier expelled its zoospores forcefully out of the sporangium (to the left in the photo). This species requires a period of cooling before the dehiscence tube will grow out of the previously ovoid sporangium. After the dehiscence tube has formed, a cold and/or freshwater shock will elicit zoospore expulsion. It may be that H. exoprolifera is a cold-season, subtropical species. Clues here are that H. exoprolifera has been found at relatively high frequency in submerged decaying leaves of red mangrove in colder seasons, in Bermuda waters, and in the northern versus southern Ryukyu Islands. See Nakagiri et al., 1996, Biodiversity and ecology of the oomycetous fungus, Halophytophthora, DIWPA Series 1:273-280.