Rapa rapa, common name the bubble turnip, is a species of sea snail, a marine gastropod mollusk in the family Muricidae, the murex snails or rock snails.
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.
Bulla rapa (Linnaeus, 1758)
Murex rapa Linnaeus, 1758 (original combination)
Pyrula papyracea Lamarck, 1816
Rapa papyracea (Lamarck, 1816)
Rapa pellucida Röding, 1798
Rapa penardi Montrouzier, 1856
Rapa striata Röding, 1798
Rapa tenuis H. Adams & A. Adams, 1858