Mollusca
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Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks. 86,600 extant species of molluscs are recognized, making it the second-largest animal phylum
Cornu aspersum (formerly Helix aspersa)—a common land snail
Shell of Marisa cornuarietis, a freshwater snail
Fossilized ammonite displayed at the National Museum of the Philippines
Diversity and variability of shells of molluscs on display
Gastropod
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Gastropods are a vast and diverse group of invertebrates within the phylum Mollusca, comprising the animals commonly known as snails and slugs. With an estimated 65,000 to 80,000 living species, they
Mollusca
…neurologically advanced of all invertebrates—and either the giant squid or the colossal squid is the largest known extant invertebrate species. The gastropods (snails, slugs and abalone) are by far the most diverse class and account for 80% of the total classified molluscan species. The four most universal…
Gastropod collage
Cepaea nemoralis: a European pulmonate land snail, which has been introduced to many other countries
The shell of Zonitoides nitidus, a small land snail, has dextral coiling, which is typical (but not universal) of gastropod shells.
The shell of Physella acuta, a freshwater snail, which is left-coiling (sinistral).