Broderipia nitidissima G.P. Deshayes, 1863
Gibbula nivosa A. Adams, 1853 Malta8,3 mm
Trochus nodulatus (FOSSIL) Moore † UK, England, Somerset
Trochus noduliferus J.B.P.A. Lamarck, 1822 Tanzania
Cantharidus nolfi G.T. Poppe, S.P. Tagaro& H. Dekker, 2006 Philippines, Aliguay Island7,7 mm
Ueckerconulus noricus (FOSSIL) A. Nützel & Erwin, 2004 † USA, Idaho, Lewis
Rossiteria nucleolus (H.A. Pilsbry, 1903) Japan
Rossiteria nucleus (R.A. Philippi, 1849) Philippines, Aliguay Island12,8 mm
Solarioconulus nudus (FOSSIL) (Münster, 1841 †) UK, England, Somerset
Gibbula obesula É.A.A. Locard, 1897 Morocco, cap Cantin
Trochus obesus L.A. Reeve, 1861
Gibbula obsconica (FOSSIL) (Wood, 1842 †) Belgium
Priotrochus obscurus (W. Wood, 1828) Qatar18 mm
Priotrochus obscurus ponsonbyi (G.B. III Sowerby, 1888) South Africa, Algoa Bay13,8 mm
Monodonta obtusa L.W. Dillwyn, 1817 South China Sea28,3 mm
Gibbula oceanica H.A. Pilsbry, 1903 Japan
Alcyna ocellata (A. Adams, 1860) French Polynesia, Topatii2 mm
Cantharidella ocellina (C. Hedley, 1911) Australia
Clanculus ochroleucus (R.A. Philippi, 1853) South Australia14 mm
Trochus ochroleucus J.F. Gmelin, 1791 Madagascar, Diego Suarez14 mm
Leiopyrga octona (R. Tate, 1891) Australia, Yorke Peninsula11 mm
Gibbula octosulcata (FOSSIL) (P. Nyst, 1835 †) Belgium
Chlorodiloma odontis (W. Wood, 1828) Australia, Yorke Peninsula13,1 mm
Stomatella oliveri (T. Iredale, 1912) New Zealand
Ethalia omphalotropis A. Adams, 1863 Japan
Cantharidus opalus (T. Martyn, 1784) New Zealand, Northland35 mm
Cantharidus opalus cannoni A.W.B. Powell, 1933 New Zealand, Chatham Islands42 mm
Trochus oppressus (F.W. Hutton, 1878) New Zealand, Plenty Bay16 mm
Lirularia optabilis (P.P. Carpenter, 1864) America
Trochus optatus G.B. II Sowerby, 1838 Philippines34 mm
Stomatella orbiculata A. Adams, 1850 Tanzania, Dar es Salaam19,3 mm
Clanculus ormophorus A. Adams, 1854 United Arab Emirates, Khor Fakkan18,3 mm
Conotalopia ornata (G.B. III Sowerby, 1903) Japan, Yawatahama
Trochus ornatus (FOSSIL) Klipstein, 1843 † Italy, Trentino-Alto Adige, Bolzano
Conominolia ovriensis (FOSSIL) A. Oleinik, 1991 †