CR 1/2 cat-sized fleas...gyeh. Even thinking about them makes me itch. While their blood drain isn't exactly an impressive amount, they can transmit any non-supernatural disease, and they tend to hang out in thick clusters or even huge swarms, so fighting just one giant flea is unlikely. Indeed, even fighting a group of giant fleas alone is unlikely, as they're pretty much always encountered as hitchhikers on giant warm-blooded animals such as dire bears and rocs.
A CR 4 hazard, the fulgurate mushroom emits 3d6 electricity damage when you come in contact with it, or 6d6 if it's hit by a cold effect. Not quite sure why this is in the main text, rather than a sidebar or an appendix, but whatever.
Fungoids are CR 3 Plants which vaguely resemble Swamp Thing and live in groups of 2 to 10 that spend each night roaming miles away from home to find food to bring back to their mushroom-studded lair. What is that food, you might ask?
Originally Posted by Tome of Horrors II
Fungoids delight in attacking creatures that wander too close to their lair. Fungoids are carnivores and consider the flesh of humans, elves, and goblins a delicacy. When food is scarce, fungoids become scavengers and feed on carrion.
Yep. Human and elf: still
the "other" other white meats.