If it sinks by itself, all it really needs is a good scrubbing with a stiff bristled brush to remove any things living in the cracks.
Some will tell you to boil it, roast it, or give it the bleach and potassium permanganate rub, but I have used rocks and wood from many areas and never had a problem.
Some will tell you to boil it, roast it, or give it the bleach and potassium permanganate rub, but I have used rocks and wood from many areas and never had a problem.