The rock creature is a non-sentient lifeform native to a class M planet located near Motherlode. They are about 100 meters tall, have very tough skin, and resemble rocky mounds when they are resting.

In 2269, they menaced an away team from the USS Enterprise which was searching for Nurse Chapel, who had been kidnapped by Harcourt Mudd. (TAS: "Mudd's Passion")