I don't have data on Conus textile, but they have been kept in aquariums
here for about 10 years.   In a study by Frank Perron, Conus pennaceus
was about 10 years.

The mortality rate for cones is extremely high during the larval stage,
and gradually decreases as their size prevents them from becoming food
for other animals.  Growth is also about asymptotic at 10 years for C.
pennaceus.  By that age, there are very few of the starting group of
velligers left.
--
                     Aloha from Wesley M. Thorsson
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