Many nematodes spend their time cruising around, sucking up stuff like little vacuum cleaners. For fungi in the genus Harposporium this is a happy situation, because Harposporium spores are designed to be sucked up. They have twisty, tricky shapes that appear to help them lodge in the throats of nematodes. Once there, they quickly germinate, penetrate through the esophageal wall into the nematode's body, and digest their hosts from the inside. Later, they pop back out to produce more spores for unsuspecting nematodes to suck up (left). We recently spent some time looking at the sexual states of these clever fungi--clarifying their relationships and nomenclature. Podocrella species have homely, dark fruiting bodies (inset, about 1 cm tall) that give little hint of the beauty and terror of their Harposporium forms.
See: Chaverri, P., G. J. Samuels, and K. T. Hodge. 2005. The genus Podocrella and its nematode-killing anamorph Harposporium. Mycologia 97:433-443.