Bare with me, I have an old 3mp point and shoot.
This pic is 3 months old.
The center rock was a chimney type that was solid and weighed 52lbs. I cored it out (what a pain) to make a volcano type air feature.
I have added more lace rock and a Fluval 303 since this photo was taken.
I need to take newer pics. Will do so and post them later.