Unknown Rock (2nd pic)?

Unknown Rock (2nd pic)?

Second picture of my dragon scale.


Unknown Rock?

Unknown Rock?

I was wondering if anyone could help me figure out what exactly this thing is. It’s all black and has little grooves in it. It’s not really sharp and doesn’t feel very strong. I’ve just been calling it my “dragon scale.” By the way, I found it somewhere on the easy coast, somewhere near New Jersey.