the bottom is just..... clear acrylic , carefully decorated by lightly scratching the surface allowing algae to give it a natural look, with some sand color paper underneath the tank xD haha , in other words, nothing special about the bottom . I'm actually not sure what they are , but looks very similar to wes's tor tor i believe, but these are more like green tengas as opposed to what wes's are , the copper masheer ... not sure .