These tiny shells are tentatively identified as a species of Cystiscus. They have occasionally been found under rocks on shallow lagoon reefs. We have not seen any in recent years, so all our photos are from old film cameras. However, John and Lynette Flynn have a nice closeup of the living shell from Majuro (first photo below).
The rest are from Enewetak Atoll.
This shot was taken through a dissecting microscope.
Created 13 October 2015
Updated 3 October 2022