The Carver Mob.

Another Ancient Mob besides the Sniffer Mob was the Carver.

They Had the unique Ability to light and move around the Overworld once it became Night Time and would find different trees to Carve them into Different designs, such as a Creeper Face in it.

Their Eggs can be found inside suspicious Gravel blocks And they are a Passive Mob, Breeding too of them with sticks. 

If A player Breaks the wooden blocks they carved the Designs will stay intact.

A Mob hatched to Carve Different Designs on any Wooden Blocks they interact with as well as being a living and movable torch Mob.