Whats the best way to clean dead rock?

[Mandosh]

I was given a box of "dead" fiji rock when I bought one of my tanks. I'm planning on using this as a base rock but now that I've had it back in SW for the last week it turns out it wasn't so dead after all (it just didn't have anything good left alive on it). Whats the best way to completely ensure I rid the rock of all the slime and hair algae before it goes into the tank?