Periwinkles are shellfish related to whelks but are much smaller. They are part of a group of snails that are sort of an evolutionary transition between sea snails and land snails. They are very small, only 1/2 to 1 cm (1/4 to 1/2 inch) big.
Periwinkles have curled flesh inside, with a tapered tip furthest part inside. They are popular in Europe, where they are often sold already cooked. The flesh will be rubbery when cooked.
They have slightly-spiralled, cone-shaped shells. Some have black shells, which may be partly bleached to a grey by the sun; some varieties will have striped shells.
They live in intertidal zones partly out of the water, and have a foot that holds onto rocks, wharves and docks. They eat algae on rocks, and decaying vegetation. when the tides go out, they are able to retain moisture in themselves so that they don't dry out inside and die. What enables this is a hard scale called an "operculum", that will be brown or black, that protects the entrance way into the shell. When the tide goes out, the scale slides shut, trapping water inside them. As well, when you pull them off rocks, their foot will retract into the shell, and the same scale will close up the opening to protect the animal inside.
There are many different species actually, such as Small Periwinkle, Flat Winkle, Edible Periwinkle and Rough Winkle. You can eat any variety of them, at any time of year, though some aren't worth bothering with as they are so small. The "Edible Periwinkle" is called edible because it's 2 to 3 cm (an inch) in size, which makes it more worthwhile bothering with.
The Edible is in fact the largest periwinkle. Its shell colour is more of a dull olive colour, though it can be tinged with yellow, or a much darker, almost black, green. It can have lighter coloured bands on its spirals.
When gathering your own periwinkles, make sure they are living in an unpolluted area.
You need a lot of periwinkles per person. And when you serve them in the shell, for people to winkle their own out, it takes a lot of time to get enough out to satisfy any appetite.
Many say cook by boiling for about 10 minutes. Others say 10 minutes is far too long because it makes them tough and chewy. Some say boil only 3 minutes, and that cooking longer makes them break apart as you try to winkle them out.
The scales are called "operculum", you don't eat these. You just use a pin to pry the scale out of the way, then use the pin to pry the meat out. You can also buy small forks with two tines on them or use a toothpick.
After boiling, they can be served with vinegar or melted butter, or you can remove the meat, and sauté it in butter or garlic to make them like Escargot.
They can be used in chowders instead of clams. Euell Gibbon's book, "Stalking The Wild Asparagus", has a recipe for periwinkle fritters.
In England, periwinkles were considered food for poor or common people.
"From March to October, wink men also purchased their stock at Billingsgate, where they could have their periwinkles prepared for them by the dealer for an extra 4d a week. Periwinkles were profitable, and wink men made up to 12s a week in summer, but in winter, when winkles were out of season and they switched to mussels and whelks, their income dropped to about 5s a week. The wink men had one of the most eccentric cries, calling, 'Winketty-winketty-wink-wink-wink -- wink-wink -- wicketty-wicketty-wink -- fine fresh winketty-winks wink wink'. Servant girls were good customers, the wink men said: 'It's reckoned a nice present from a young man to his sweetheart.' Old people too 'that lives by themselves.. and [have] nothing to do pertickler' also favoured winks, as extracting each one with a pin was 'a pleasant way of making time long over a meal'. " -- Flanders, Judith. The Victorian City. London: Atlantic Books. 2012. Page 283, talking about London in the 1850s to 1860s.
The word periwinkle came to also mean in slang a small penis.
Periwinkle comes from the Old English word "pnewincle."
There is also a plant called "periwinkle" which is, of course, unrelated.