Lava rock plates. 13 pieces, large and small. Compared to a ruler in image 2. Please use it as a size reference. Used in an aquatic plant tank. They haven't been washed, so there is some dirt. These are inexpensive, so no claims or returns are accepted. *Please understand that there is a possibility of breakage during shipping. As shown in image 1, I used them stacked to create a tunnel. I plan to ship them packed in a Takkyubin Compact box. Thank you.