Thanks. I have three large 25-30lb pieces of Marco shelf rock that were some of the most interesting shapes I'd ever seen - so I had to have them, naturally (fortunately they fit as I bought them without measuring first!) There's an assortment of smaller Marco base and shelf rock that I've used to create three main arches (left, right and far right) and then I have an assortment of rock "islands" that are slowly but surely turning into either zoa/paly or rock flower colonies.I really like the open ledges you created with your rock scape for your coral additions