They look similar to feather/lava rock except feather rock is black and dark grey. You can buy feather rocks for .60 cents a pound around here at landscaping stores. I spent $40 and got so much that I can't use them all so I put the rest outside in my flower beds. I drilled holes in them to make caves. They are very easy to reshape and break into smaller pieces too. I cut the huge ones with a saw and turned one large rock into 4 medium size rocks. So the possibilities are kinda endless. They are so light weight thateven the extra large ones will float so I had to silicone flat rock to the bottom of them to keep them down. I love them. I have them stacked on top of each other. Plus feather rock is very porous and great for benefictial bacteria. I liked the dark color too. My cichlids love swimming around them and going inside the holes I drilled. They seem to prefer the feather rock over the Mexican Beach Stones that I also have in my 55 gallon. I prefer a natural look. I don't think the cichlid stones will look real once they are placed inside a tank, but maybe I'm wrong. I think the larger cichlid stones look like an alien's head, lol, at least that is what I thought when I first saw them on the website. Well, that's my two cents!