Yup, this is ginger tea. I've used the same tea in the past, but never had any problems. I'm using a piece of thin cotton cloth for the cover. It's weird, huh? I'm mostly curious if anyone has ever seen anything like it before.
I went on a week long vacation and when I got back, my kombucha was covered in little black specks almost like super fine coffee grounds were sprinkled all over it. I threw it all out, boiled my jug, and tried again with a culture from a clean batch. Obviously I didn't sterilize the container...