My buddy came back from a trip to ***** Cana, Santo Domingo and he brought back a couple pieces of live rock and conch shell. I haven't seen it but he told me he got it for me to put in my tank. That's very thoughtfull and all but I told him I just can't put anything in my tank. What's the best way to sterilize/clean these pieces so that I can put em in my tank? Or should I just tell him thanks but no thanks?