Slinking their way through cold swamps and bleary marshlands, or sometimes even dungeons and caverns, gray oozes consume any organic materials they encounter. Despite its lack of intelligence, the gray ooze is a most problematic creature due to its transparency. While the ooze cannot easily climb walls or swim, its habit of lurking in the thick mud that lines the banks of marsh pools or lying in harmless-looking pools on dull-colored dungeon floors makes it dangerously easy to overlook and step on.
Some sages believe that the gray ooze is the result of a failed alchemical experiment, while others postulate that the first gray oozes spontaneously arose from a cesspit of magical detritus. Of course, these theories that gray oozes are not living organisms, but rather the alchemical result of an unfortunate mixture of rare caustic fluids and magical waste, are derided by many who dwell in areas plagued by the creatures but which do not have a long history of magical pollution.
Gray oozes are immune to fire, cold and have immunity to poison, sleep effects, paralysis, polymorph, and stunning. They are mindless and technically blind, but use blindsight to locate their prey. Because they lack any discernible anatomy and have no internal organs, they cannot be harmed by precision damage.