Dear friends

Conus marmoreus definitely has an operculum. However, it is not rare to
observe individuals of this or any other species lacking an operculum.
Alternatively, from time to time I have observed individuals having two
operculi! I believe that the operculum may suffer from damage during the
live of the animal, and eventually falls off, being replaced by a new one.
This process takes time. For this reason, it is not unusual to see large
individuals having what seems to be a very thin and small operculum, and
smaller individuals having a larger, thicker one. At least, this is my
experience with the collecting of many individuals of varied species of
cones, mainly in the Cape Verde Islands. The observations that I mention
were mostly made on species of the venulatus group, but I have also
observed Chelyconus ermineus individuals having no operculum, so this is
quite common I think. However, I must mention that there are species which
indeed lack an operculum, specially in certain genera of Conilithidae or
Conorbiidae.
Warmest regards

Manuel Jimenez Tenorio
Jerez, Cadiz, SPAIN

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