I ordered about 45 pounds of carribean rock last year. Mine sucked too. It looked like concrete too. I only have one small piece left in my tank, only because one of my polyp colonies spread all over it. The whole time I had this rock in my tank, I never saw any signs of life come from it. I sure there was bacteria in it, but not much else. Anyway, the rest sits dry in a tub with the rest of my extra base rock now.