| Title | Periwinkles |
| Caption | Periwinkles found at an dig site, where they were being used for jewelry. |
| Source | Dr. Charles Ewen |
| Type | Photograph |
| Origin | Digital camera |
The OED defines "Periwinkle" as: "Any of numerous herbivorous gastropod molluscs of the family Littorinidae, which have a spiral shell and are abundant in the intertidal zone of rocky coasts."