A good scrub to clean off any algae or dirt and a rinse with boiling water should be sufficient. Just don't stick them in boiling water, rocks have the potential to explode from air bubbles trapped inside them. Pouring the boiling water over them should be good enough to kill any nasties that may be on it.
Thank you so much, I thought I'd have to do something special.
How can you clean sand for aquariums? I'm going to siesta keys in a week and could maybe us the sand. Would it work if the sand is SW and I put it in FW?
I wouldn't. Not only does it have salt in it, but there could also be pollutants in it if you're getting it from an area where lots of people visit. If I were you, i'd go for pool filter sand or play sand. 6-10 bucks at a local hardware store/home depot/lowes.