CaribSea Zen Garden Aquarium Gravel (40 lb, ¼–⅜″) – A natural river pebble substrate that brings a tranquil, Zen-like aesthetic to aquariums or decorative water gardens. The stones range from 1/4 to 3/8 of an inch in size and feature earthy hues and smooth surfaces. Ideal for freshwater setups, this heavy gravel creates a stable base for plants and ornaments, supports beneficial bacteria colonization for biological filtration, and gives aquascapes a polished, serene look reminiscent of a Japanese rock garden.