Giant Gastropod egg capsules of Adelomelon Brasiliana on the beach of a lagoon, Mar del Plata, Buenos Aires, Argentina.
The Gastropoda or gastropods, more commonly known as snails and slugs, are a large taxonomic class within the phylum Mollusca. The class Gastropoda includes snails and slugs of all kinds and all sizes from microscopic to large. Wikipedia
Adelomelon brasiliana is a species of sea snail, a marine gastropod mollusk in the family Volutidae, the volutes. Wikipedia