The operculum is a corneous or calcareous anatomical structure like a trapdoor that exists in many groups of sea snails and freshwater snails, and also in a few groups of land snails; the structure is found in some marine and freshwater gastropods, and in a minority of terrestrial gastropods, including the families Helicinidae, Cyclophoridae, Aciculidae, Maizaniidae, Pomatiidae, etc.
Buccinum undatum, the common whelk or the waved buccinum, is a large, edible marine gastropod in the family Buccinidae, the "true whelks".
Tonna galea, commonly known as the giant tun, is a species of marine gastropod mollusc in the family Tonnidae. This very large sea snail or tun snail is found in the North Atlantic Ocean as far as the coast of West Africa, in the Mediterranean Sea and the Caribbean Sea. The species was first described by Carl Linnaeus in 1758.
Fasciolaria tulipa, common name the true tulip, is a species of large sea snail, a marine gastropod mollusk in the family Fasciolariidae.
Bathytoma luehdorfi is a species of sea snail, a marine gastropod mollusk in the family Borsoniidae.
Kurtzia aethra is a species of sea snail, a marine gastropod mollusk in the family Mangeliidae.
Xanthodaphne membranacea is a species of sea snail, a marine gastropod mollusk in the family Raphitomidae.
Cymatosyrinx carpenteri is a species of sea snail, a marine gastropod mollusk in the family Drilliidae.
Haliotis queketti, common name Quekett's abalone, is a species of sea snail, a marine gastropod mollusk in the family Haliotidae, the abalones.
Buccinum glaciale is a species of sea snail, a marine gastropod mollusk in the family Buccinidae, the true whelks.
Vexillum styria is a species of small sea snail, marine gastropod mollusk in the family Costellariidae, the ribbed miters.
Buccinum baerii, common name Baer's buccinum, is a species of sea snail, a marine gastropod mollusk in the family Buccinidae, the true whelks. The epithet is written by some authors as "baeri".
Buccinum lyperum is a species of sea snail, a marine gastropod mollusk in the family Buccinidae, the true whelks. A few authors use the epithet "lyperium"
Buccinum strigillatum is a species of sea snail, a marine gastropod mollusk in the family Buccinidae, the true whelks.
Buccinum tsubai is a species of sea snail, a marine gastropod mollusk in the family Buccinidae, the true whelks.
Phasianotrochus apicinus, common name the pointed kelp shell, is a species of sea snail, a marine gastropod mollusk in the family Trochidae, the top snails.
Lirularia yamadana is a species of small sea snail, a marine gastropod mollusk in the family Trochidae, the top snails.
Drilliola difficilis is a species of sea snail, a marine gastropod mollusk in the family Borsoniidae.
Nassarius crassiusculus, is a species of sea snail, a marine gastropod mollusc in the family Nassariidae, the Nassa mud snails or dog whelks.
Lirabuccinum dirum, commonly known as the dire whelk, the spindle shell or the spindle whelk, is a species of sea snail, a marine gastropod mollusk in the family Buccinidae, the true whelks. It used to be known as Searlesia dira and Buccinum dirum before being transferred to the genus Lirabuccinum.
