Since several of you have asked, here is the rest of the story, at least what there is of it:
Limpet shells are those shells that look like Chinese straw hats.  Sea animals, real ones, live in them.  We can find them in the shallows along many parts of our coast.  They are collected live, boiled to evict their owners, and thus not acceptable for strict vegetarians.  If need be an emory board is used to smooth the edges.  They are worn over the sore nipples, and keep them moist in leaked milk while also keeping them everted and preventing irritation from clothing.  The shells are porous to some degree, but are inappropriate if mother has yeast.  Of course, they are removed during actual breastfeeding!.
They have been known as a folk remedy for sore nipples from before modern hospital obstetric care, and had been all but forgotten.  They are now experiencing a big revival after someone remembered them and brought them to a ward where their effect soon became legendary-- we may have to start aquaculture of limpets to keep ourselves supplied!
The natural variation in size gives us options for different sizes and shapes of breasts.
The National Institute of Public Health in Norway is about to analyze the mineral content of some samples to see if that could be part of why they seem to work so well.  But as one LPN on a postnatal ward said,
Don't analyze them too much!  They work so well now, and if you find out they don't have any value, they'll stop working."
We are also discussing how to design a study to evaluate their usefulness, but we are hesitant in part because they do work so well and are seemingly so harmless-- especially compared to all the useless things we normally do for sore nipples--  we would rather not find out they are useless too!
I like them because they seem to help keep BF in the realm of folk knowledge, normalcy, something we can use seashells to help with.  And mothers generally find them comfortable to use.  They seldom are used more than a day or two, usually at that time when physiologic engorgement is at its peak, and it is much easier for baby to latch on if the areola isn't edematous and rigid, which it isn't with these.
If anyone else knows of any other places where such things are in use or at least known, please let me know.
Rachel Myr

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