[bluespotjawfish]

I place small rocks right on top of it. They will attach to the smaller rock, then you slice it off the base rock and sell the small fragged rocks. The base rock may continue to grow it, but if you persistently do this, it eventually works its way up to the smaller rocks permanently (where the light is). If you can find another way to reduce the amount of light that it gets, that will slow the growth too.