Icelandic lava rock has a rough pitted exterior the uneven holey bumpy surface sometimes have smooth shiny structures which provide somewhere for plants to colonise this adds an exotic feel to your aquarium and is also a natural method of water filtration the majority of lava rocks are a matt dark colour ranging from black to violet to red some are slightly yellow lava rock is very light in weight and easy to move around so you can create stunning wild and romantic scenes you can also