Yeah, sorry everyone, but I agree with skip. Other than a hose down to remove unwanted dirt or maybe an overnight soak in plain water to make sure I'm not bringing in anything like termites or something, I just put the rock or branch in the cage. Been doing this for many years, never had an issue, but thats just my experience. I'm more likely to wash/bleach items from the store, because you never know what they may have come in contact with while in transit.