It is not porous at all. They mention this also. Only the surface will carry bacteria. It’s solid otherwise. And they also state that if your display is only using this product, you should supplement with biological media elsewherei am curious, how porous is the rock?
It is a liquid resin poured in a mold. So there are no pores
It’s a good thing. It means no little worms or pests are going to be making their way in and using it as a hotel