These dyed shells are another great seashell for crafting or home decor projects. Pearl Umbonium Seashells are commonly known as Button Top Shells and are a small round shaped pearl shell. They come in a bulk bag, which makes it easy to buy for shell crafts and fillers. Umbonium, is a genus of sea snails. The shells of the species in this genus are low-spired and shaped like a button, and the umbilicus, or hollow cone-shaped space, of the shell is often completely covered with a thick and smooth callus. Bring the beach home with one of our unique seashells, offered in a variety of sizes. Whether it's a souvenir from a recent vacation, decorative accent for any room, or part of your coastal craft, these high-quality shells are some of the lowest prices around.