46 selected
- Not filled in
- Obba scrobiculata Pfeiffer, 1842
- Obesula borbonica Jousseaume, 1898
- Obesula levukensis (R. B. Watson, 1880)
- Ocinebrina aegeensis Aissaoui, Barco & Oliverio, 2017
- Odetta bosyuensis (Nomura, 1937)
- Odontocymbiola americana
- Odontocymbiola americana (Reeve, 1856)
- Odontocymbiola simulatrix Leal & Bouchet, 1989
- Odostomia vaga Laws, 1939
- Oestophora barbella (Servain, 1880)
- Oliva caerulea (Röding, 1798)
- Oliva concavospira G. B. Sowerby III, 1914
- Oliva concinna Marrat, 1870
- Oliva efasciata Dautzenberg, 1927
- Oliva incrassata (Lightfoot, 1786)
- Oliva keeni Marrat, 1870
- Oliva miniacea (Röding, 1758)
- Oliva oliva (Linnaeus, 1758)
- Oliva reticulata
- Oliva rufula Duclos, 1840
- Oliva sericea P. F. Röding, 1798
- Oliva sidelia P. L. Duclos, 1835
- Oliva staleyi Perini, 2011
- Oliva tigridella Duclos, 1835
- Oliva vidua (Röding, 1798)
- Oliva westralis (Petuch & Sargent, 1986)
- Olivella biplicata (G. B. Sowerby I, 1825)
- Ophioglossolambis digitata (G. Perry, 1811)
- Ophioglossolambis itsumiae Lum, 2021
- Orthodus Oblicus
- Ostrea megodon Hanley, 1846
- Otala lactea (O.F. Müller, 1774)
- Otala lobethana (Debaux, 1882)
- Otala lucasii G. P. Deshayes, 1850
- Otala polita Gassies, 1850
- Otala riffensis P.M. Pallary, 1903
- Otala tingitana (Paladilhe, 1875)
- Ovatipsa chinensis
- Ovis orientalis
- Ovula ovum
- Oxychilus alliarus (Miller, 1822)
- Oxychilus draparnaudi (Beck, 1837)
- Oxymeris crenulata (Linnaeus, 1758)
- Oxymeris maculata (Linnaeus, 1758)
- Oxyperas elongatum (Quoy & Gaimard, 1835)
- Oxystele impervia (Menke, 1843)