When I was young I had a growth in my jaw. A lump that I could move around with !

I had it ever since I was a little kid up and over the years it shrunk and went away. It was just like some kind of loose mass of something that could move freely and I could move it to both inside and outside my jawbone. I never told anyone about it as it didn't actually bother me. I have pretty good teeth. It was below where the molars are off the bottom of my jawbone. I also have noticed that if you feel the bottom of my jawbone there is like a slight dip in the structure there but on both sides so its probably just how my skull is shaped. I have seen this in some but not all pictures of skulls on the internet but on the side where the growth was its somewhat deeper.

I always wondered what it was. My mouth is fine save for a small torus on that side.