Take a quick moment to think about weird places teeth can grow and there’s a good chance your first thought will be something like outside of a cheek. You may also picture a guy with a mouth looking like Jaws, two rows of teeth, some of them jutting out of the top of his gums. But really, any location that’s closer to the mouth is just too safe a guess.

In the below video, Discovery News’ Laci Green goes through some of the most bizarre, and disturbing, places teeth have grown. From teeth growing in a brain tumor to some of them becoming full grown in an eyeball. Mother Nature shows us that teeth can get pretty creative when they think outside the box — or the mouth, rather. But teeth definitely aren’t relegated to the head only, and you’ll have to watch the video to see one of the weirdest spots they’ve grown. A hint: Teeth.

But really though, how do teeth stray from the mouth and grow in the most random of places? Well, many of them grow in tumors known as teratomas, which are derived from the Greek teras, meaning “monster.” These tumors contain several types of cells taken from different types of tissue. Essentially, they grow uncontrollably, and into various forms of tissue, from hair to teeth to even an eyeball.  

Though they sound scary and intense, they actually contributed to the discovery of human embryonic stem cells, which have since given scientists the ability to grow new organs, among many other medical uses.