– Soft river stones that are a dark grey when dry and pitch black when wet. – High-contrast gravel that creates a striking visual effect when combined with green or reddish plants. – Perfect for creating stunning aquascapes or stream biotope or for use as a complementary substrate with black stones or boulders. – Perfect match with Black Venom Nano Boulders and Nano Rocks, and with Black Venom Boulders and Stones.