A nonliving, nonsentient structure that grew from a meteorite, this inanimate "monster" forever obeys the whims of the first sentient being it comes into contact with. Its hollow, rocky shell conceals a large mass of red jelly that behaves remarkably like a living creature, engulfing and dissolving any organic substance within reach. This protoplasmic blob can move freely up to a mile from its shell, but will crystallize and disintegrate if forced any farther.
The Grenzo's jelly is highly susceptible to freezing, and recoils from sources of extreme cold. A faint throbbing sound can be heard from its shell.
The second of three inanimate meteoric phenomenon with honorary "monster" status, an idea I'd planned off and on for some time now. This one is rather blatantly based on The Blob, or rather, the space-rock that unleashed the Blob