The fungal crawler is nice for being the kind of monster that makes subterranean ecosystems work. Part insect, part plant; able to either scavenge and live off radiation; and able to fill countless ecological niches thanks to its flexibility and hardiness (sort of like finches in the Galapagos or eucalyptus trees in Australia). If a party spends any time below the surface, they should eventually run into some of these—and the creatures that prey upon them. (And they fact that fungal crawlers are aberrations, not vermin, may be a boon or an unpleasant surprise to certain rangers and druids, depending on their character builds.)
On the subterranean Black Mere, troglodytes fish from small bucket-shaped boats while fungal crawlers skim like water striders over the glassy lake surface. The troglodytes often hunt the fungal crawlers…but the fungal crawlers are just as happy to hunt the troglodytes when the odds are in their favor. (The aberrations’ Great Fortitude and plant defenses are no small help in this regard.) Both sides will attack any surface dwellers they come across on sight—even ceasing mid-meal to do so.
Certain varieties of fungal crawlers are delicacies to the drow—they smoke the creatures into quiescence, bind them, and then eat their fungal tops while the crawlers are still alive (killing them in the process, of course). Drow farmers always need servants to harvest more fungal crawlers, but these farmers’ jealous neighbors are equally as likely to kill such servants as poachers.
A catastrophically poor attempt at training fungal crawlers led the Broken Foot kobolds to create an annual festival: the Hopping of the Bugs. Kobolds come from miles around to watch their fellows ride (or outrace in a panic) fungal crawlers through an abandoned svirfneblin village. That upworld adventurers often use the village as a safe haven is a bonus.
—Pathfinder Bestiary 2 127
Gah. 13-hour workdays.
Shouldn’t they be called fungal hoppers? Fungal crickets?