Mine was a dark brown color. Hac no "burrs" to it but was very rough along the surface. My Dr. Sent it out to be analyzed and it came back as calcium. Said the dark color was from it being inside so long combined with the dark colored liquids (coffee, tea, etc) I was drinking.
Best of luck to you.
Thanks, I'm just glad it's out. It's been sitting very close to the exit for the last couple of weeks. I'm sure more to follow unless they go get them or put me in the ultrasonic tub.