I was given some very porous rock and told that it had probably been LR
at some point, but he couldn't remember if he had used it in his tank or if it had come along with something he bought. It looks remarkably like my Fiji, and is in decent shapes.
How do I know if this is made of an appropriate material, and how would I prepare it for my aquarium (setting up, nothing live in it yet)? Is it better to not take my chances and just leave it out?
I apologize if this has already been covered. I looked through the archives, but didn't see an answer to my question.