Help with identification

[Sunshine2036]

I purchased quite a few pieces of dry rock and on this particular piece I found what looked like a calcified layer of I don't know what. I powerwashed it after a hydrogen peroxide treatment and it's still there. Can anyone help me identify it and if it safe to add to my tank?

 

[Idoc]

No clue what it is, but it's calcified on the rock and part of the live rock structure. It'll be ok. If in doubt that it might be a type of organic material, then soak it in water for a couple weeks and perform a "cure" while testing the water for ammonia. If no ammonia, then it's not organic.