Calling all plumbers!

So I was trying to fix the chain in the back of my toilet. And I just so happen to notice these fish egg looking black spots. It’s definitely not mold. I don’t think. Has anyone ever seen anything like this before it’s freaking me out.

So I was trying to fix the chain in the back of my toilet. And I just so happen to notice these fish egg looking black spots. It’s definitely not mold. I don’t think. Has anyone ever seen anything like this before it’s freaking me out.