16:34 Feb 13 

Yes, that's great. What a wonderful bit of research Giles.

14:04 Feb 13 

Yes, it's a dialect term at Grado for the pelican's foot shell (as I have just ascertained!).

13:33 Feb 13 

Thanks a lot, this is very useful. It is strange that I found no information about it on the net. I should have another name then and chiave di San Pietro may be un termine dialettale?

11:45 Feb 13 

Giles, after seeing some paguro/hermit crab snapshots, the similarity to a key of sorts does exist, especially if the hermit chooses a long shell as his home. The fantasy of gourmets is endless...

09:04 Feb 13 

There is a published translation of Microcosmi (Microcosms, translated by Iain Halliday, Harvill Press, 1999), which gives these shellfish as "abalones, pink and violet tellins, scallops, bluish limpets".

I don't know how reliable this is. "Telline" are called "wedge shells" in English, and their colour is usually described as purple, rather than "violet". "Chiave di San Pietro" is not a kind of scallop. I phoned a restaurant in Grado where they were able to describe the creature. It's got a long shell - think hermit crab - with a couple of protuberances at the bottom that make it look vaguely like a key.

FWIW