Rapa rapa (Linnaeus, 1758)
50.4mm

Rapa rapa is a thin, fragile shell that spends all its time completely embedded in cavities in the soft coral Sarcophyton. Usually, there is no discernable hole from the chamber where the shell lives to the outside, although one does open up to enable the shell to reproduce. Occasionally you can find these holes, either in the side of the soft coral colony or right in its top.

It seems predators can find their way in as well. This soft coral colony was found with a hole apparently bitten in the top of the colony, exposing a Rapa rapa. The shell has holes and has been dead for some time.

Another hole found in a soft coral colony revealed the broken fragments of a Rapa rapa. I suspect a fish bit its way in and broke up the shell.

A cluster of Sarcophyton colonies on a lagoon rock. Very likely some of the colonies contain Rapa.

Created 17 December 2017
Updated 30 March 2020

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