Felcaps

A broad spectrum of fungus that feeds on dead animal mass when other scavengers can't reach it.
Felcaps, so named for their dense populations in lightless areas that often house (or spawn) fel crystalites, are large colonial mushrooms with wide, umbrella-shaped caps and short, squat trunks. They are voracious consumers of putrefying flesh, so anywhere normal scavengers cannot reach to strip an animal carcass quickly enough, felcaps sprout and consume everything left, including the softening bones.
Felcaps do not sprout where there is no flesh to feed upon, so they are reliable indicators of a recent corpse (or a place where corpses recur frequently). There are two theories on how they propogate between deaths - the more likely is that flies and other insects carry spores from corpse to corpse, while the other is that they have integrated themselves so densely into the delicate lace of roots in forests that they can simply spawn anywhere food occurs.
Most felcaps are a dull, nameless color that mixes grey, desaturated brown, and dull red. Their exact features vary across biomes and nations - some have dark or light spots or patches on the cap, for example - but their shape and feeding pattern marks them as the same species regardless.
Felcap flesh is dense, wet, and pungent; they are not poisonous to humans, but they have an acrid taste and foul scent, making them undesirable food sources to most animals. Most cultures have a poor opinion of them as grave-markers and do not interact with them, but it's possible to harvest them, dry them (usually by smoking them like one would jerky), and add them to soups or stews as a meat substitute. They are heavier than most other fungus and can have either a rubbery (like calamari) or stringy (like jerky) mouthfeel, depending on how they're prepared.