Mosaic Part is a term used to describe the components of a mosaic. The two main parts are TESSERA (7 letters) and TILE (4 letters). TESSERA are small pieces of glass, stone, or other material that are cut into shapes and arranged to form a pattern. TILE is a flat piece of material, usually ceramic, that is used to cover walls and floors. Both TESSERA and TILE are used to create mosaics, which are decorative artworks made up of many small pieces.