Cosmos Sea Shells Cosmos Bipinnatus is a flowering, herbaceous annual plant native to Mexico. Growing Cosmos Sea Shells from seeds is the easiest and cheapest way to establish this garden annual that is also commonly called Common Cosmos and Mexican Aster. Sea Shells Cosmos blooms with large, 3 inches in diameter, daisy-like flowers that have yellow centers and petals with a very unique color pattern which resembles sea shells. Growing on a tall stems with fern-like leaves, Cosmos Sea Shells flowers provide a very delicate pastel of pink, white, carmine, and rose colors. Cosmos blooms nonstop from summer to first frost attracting bees and butterflies.