Hi everyone. I got a new (to me) 20 gallon tank with a couple clownfish and a sassy cleaner shrimp 2 months ago and have been working to get everything in the tank established and happy. The previous owner gave me a couple extra rocks that were not in the tank and I am unsure of their history so am being cautious before using them. I have put this one in hydrogen peroxide for the last 3 days and took it out to use my microscope camera to see what it is still on it. I am sharing photos to get input about how to move forward to prepare this rock for my tank or if the stuff that is still on it should even be put in a tank. The rock was sitting in the previous owner’s driveway when I went to go pick up the tank and has been sitting on my bookcase out of water for the last two months. Thanks in advance for your experience and ideas.