Jellyglops are small, fist-sized creatures that look like glops of jelly.  They dwell on the floor, sides, and ceilings of caverns.  There are many sub-species of jellyglops, including luminescent, camouflage, calico, striped, spotted, and translucent.  Jellyglops are not particularly intelligent animals, and prefer to stay put in one spot for many days.  They can sleep for up to three days in the same spot without waking, and naturally absorb moisture and minerals from rocks.  Luminescent jellyglops are often used as inexpensive alternatives to lanterns.  You simply buy a bundle of jellyglops, a large slate of limestone or similar rock, and place them in the desired dark area.  When the jellyglops have exhausted all resources on that particular rock, you throw it out and buy a new one.