Anybody know anything about this rock or where it comes from?
Would it be safe for my tank? I took them to the car wash and they had a lot of rust on them that washed, and washed, and washed. I think I got them pretty clean. And no, I didn't use any soap on them! I hope they wouldn't turn the water rusty.
I would like to use them in a iwagumi scape.
Here are the ones I found...