Are these Dun Sentinel Snails?

Are these Dun Sentinel Snails?

Observation - Are these Dun Sentinel Snails?. Description: Small snails, 3-5mm in length found just past the high tide mark of the Humber estuary, in between areas of reed, sea aster and damp grass. Hope someone can help as I can't find much info on these. Thanks.

Small snails, 3-5mm in length found just past the high tide mark of the Humber estuary, in between areas of reed, sea aster and damp grass. Hope someone can help as I can't find much info on these. Thanks.