Recently some (non-malacological) friends visited Cuba. I had asked them to be on the outlook for souvenir shops selling shells as ornaments.
They sent me two pictures of necklaces made up by Polymita shells. “These were found only the far eastern side of the island, next to Parque Nacional Alejandro de Humboldt. They occur on many coffee plantations were they seem to be collected for making these necklaces”.
Although this may seem reassuring (“collected only in coffee plantations”), I will ask more details when I see my friends next time. Keep you updated.