Why are there hidden drawings in Jehovahs witness publications?

I didnt believe it until I read an article about this so I went and bought heaps of old JW publications and looked over the illustrations, I found things like a horned beast in a tree, the word DIE written on a wall, a womans /nipple in a tree trunk, many ghoulie faces in mountains and clothes, skulls, a few of rams horns , one creatively added to a womans hair etc. And no, it was not like looking for pictures in clouds, I showed these independently to family and friends who also confirmed that they were most definitely without a doubt there though there are some which were hard to definitely confirm.