Faciolopsis buski

Morel mushroom spores in feces (unstained, high power). Though not often specifically recognized or identified as such, the spores of various edible mushrooms may be encountered in human fecal specimens. In particular, spores of morel mushrooms (genus Morchella) may be confused with small trematode eggs. The spores are generally in two size ranges. The larger spore is approximately 58 µm long by 15 µm wide, and the smaller one is 23 µm long by 13 µm wide. The larger one is perhaps less likely to be confused with a helminth egg. However, the size and shape of the smaller spore have led to such spores being misidentified as heterophyid-type trematode eggs. The lack of an operculum and a miracidium in such spores distinguishes them from trematode eggs.