Cacao leaves , from the Theobroma cacao plant, are used in terrariums to enrich bioactive soils, provide natural hiding places, and promote the growth of beneficial microorganisms. They improve humidity and provide support for certain insects and scavengers. In aquariums, they release tannins that help acidify the water and have antifungal and antibacterial properties. Their natural appearance makes them an excellent addition to bioactive habitats.