Cone shells are considered the most beautiful shells in the world, and on the beaches of Seychelles you may find them washed up, normally empty.
While alive, their shells are even more beautiful and delicate. However, you are best off leaving them undisturbed: Cone shells may inject you with a nasty poison, and some are outright deadly. So unless you really know what you are doing, don't pick them up. Leave them alone and just watch them going about their deadly business of spearing small fish.
Check the internet on "cone shells" and you may find some interesting facts. Perhaps you will also enjoy bringing a field guide or reference book about shells and mollusks? You'll be very busy on Seychelles' beaches then.