Quite a small periwinkle specimen, with grooved lines on shell,
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Melarhaphe neritoides is a very small winkle with a high pointed spire and flat sides. The shell resembles a grape pip. The shell is dark bluish to blackish-brown in colour, occasionally with spiral banding or vertical stripes on the last whorl. Pale shells may also occur, but your posting has ridges which M. neritoides does not.
Have a look at these two sites & see what you think.
Yes , you right it definitely not the same creature! Ta v
Lat/Lng: 50.4047, -5.1292
OS grid ref: SW777607