The foundation of my house is made of boulders, do those count?

I have several dozen free of metal contamination that are in my turtle tank and aquariums. I found them on hikes, at beaches, and from lots of different regions.

I also have a bunch that have metal contamination (slag or natural deposits) which are in a jar because they kill invertebrates so can’t have them in the tanks.

Other than that I have lava rock on top of most of my plants.