ya just lays in the bottom just make sure the pieces are snug, dont make my mistake and use slate the porous surface makes a perfect breeding ground for algae growth. when its bad (like in a few pics ive posred) it takes 3+ hours to scrub clean and makes the water so dirty you cant see the fish in the tank...seriously lol, try finding a glass surface tile or porcelain tile which the algae doesnt have such a great place to grow too