I am nowhere near a geologist, but those look like igneous rocks to me. Extrusive, maybe, since I can't see the grains. Those nooks and crannies could be the result of some type of folding, but they look more volcanic in origin to me, especially the last sequence. Also, if the rocks were made of carbonate, I would certainly put some sort of warning in there about their inappropriateness for some types of freshwater aquariums. Just a thought,
TB (Remember: NOT a geologist) |