Gray ooze

A gray ooze resembles a thick puddle of gray sludge, roughly 8"(20 cm) and up to 14'(4.27 m) across, that closely resembles wet stone or an amorphous rock formation. They consume any organic matter they encounter.

Lairs
Gray ooze is a living form of slime that slinks through cold swamps and marshes. They can also be found in caverns and dungeons. They are mindless scavengers who drag themselves around caves and sewers and absorb and digest whatever they come across. Unlike other oozes, the gray variety cannot move on ceilings or walls, hence it is left to slide its way along subterranean floors.

Reproduction
Gray oozes reproduce by breaking small driplets off of them after a meal, which later grow into gray oozes themselves.

Combat
While possessing an immunity to magic, fire, and cold, the gray ooze cannot speak. They attack by striking until its prey is either dead or unconscious, moving on top of them afterwards to digest them from within. Acidic secretions of the gray ooze corrode metal at an alarming rate; as a result, blacksmiths also sometimes use jarred gray oozes to meld ore into the right shape. Gray oozes are particularly feared due to the fact that they are transparent. This makes them difficult to detect while they are still or moving slowly.