Proline Decorative Concrete Systems 3CQS 36" x 36" Coquina Stone with Sea Shells Concrete Stamp. Coquina Stone is a sedimentary rock mainly composed of seashells or coral that takes years to produce and is expensive to process. Prolines Seamless Coquina Stone with Sea Shells can provide you a charming aquatic texture with the low cost, durability and endurance of concrete. This piece is perfect for pool areas, as it has a natural traction when wet to prevent slippage. Accented with an array of chevron sea shells, starfish and sea horses, Coquina Stone with Sea Shells will add a beautiful compliment to any outside area. Check out our Dolphin Border Art and our Tropical Fish Border Art for enhanced charm.