Brown Mold

Brown mold feeds on warmth, drawing heat from anything around it. A patch of brown mold typically covers a 10-foot square and the temperature within 30 feet of it is always frigid.
Brown mold is immune to fire, and any source of fire brought within 5 feet of a patch causes it to instantly expand outward in the direction of the fire, covering a 10-foot-square area (with the source of the fire at the center of that area). A patch of brown mold exposed to an effect that deals cold damage is instantly destroyed.

Scientific Name
Fuscus Mold