Rock creatures
The rock creature was a non-sentient lifeform native to a class M planet located near Motherlode. They were about a hundred meters tall, had very tough skin, and resembled rocky mounds when they were 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")