JBL ProScape Volcano Mineral 3lVolcanic rock soil, stable base ideal for stone or wooden structures: special substrate for aquascaping aquarium backgroundBase substrate for natural aquariums: porous volcanic rock ensures water circulation in the soil. Provides organic nutrients for plant roots.vigorous plant growth: optimal oxygenation and water circulation due to open pore structure. Secure, non-slip base: the volcanic rock granules interlock with each other. Ideal for a non-sagging base.Included in delivery: 1 bag of ProScape Volcano Mineral