What links a flower, a snail and a colour?

I was out for a run when I saw this Lesser Periwinkle, and then pondered why this naturalised garden flower has the same common name as the small edible whelk, the Common Periwinkle.  The delightfully named uselessetymology.com tells me that they have a different etymology and come from different origins, but both imply curling, bending or entwining. The plant name comes from its creeping growth form (from the Latin) and the mollusc's name describes its curved shell (from the Old English-Germanic).
Periwinkle is also a colour (1st recorded use in 1922).
Or if you prefer, the Periwinkle flower might get its name from 'pervinka', the Russian name for the flower, derived from 'pervi' or first, as it is one of the first flowers of spring.  (That at least is true!)