Unidentified shell

Unidentified shell

Observation - Unidentified shell. Description: Found washed up on the shore at Harwich.Dimension 38mm x 30mm x 20mm. Help with ID would be appreciated. It appears that its position on the shore is within reach of oystercatchers given the damage on the lip

Found washed up on the shore at Harwich.Dimension 38mm x 30mm x 20mm. Help with ID would be appreciated. It appears that its position on the shore is within reach of oystercatchers given the damage on the lip