This photography represents cystolith in epidermal cells of Ficus Elastica. Cystolith is a botanical term for the inorganic concretions, usually of calcium carbonate, formed in a cellulose matrix in special cells called lithocysts generally in the leaf of plants of certain families, such as Ficus elastica (which is shown in the photorgaphy) or in other plant families - Moraceae,Cannabaceae etc.