Danish, Svendborg Seal, Image & Held by Ged Dodd.
Found in Kinghorn, Scotland, 18 x 16 x 4mm, 5.6g.
SVEND..O... curved around the perimeter // snake
One side has SVEND.... the other side has a snake rather like the symbol of Aesculapius as used in the medical profession. Rust stains show a wire insert was used. See SVEN Seal, Image & Found by Tatooed Detectorist.
From Paul Cannon, "The three examples on the following Danish site suggest that this type of seal relates to the Danish town of Svendborg in south-central Denmark Nordek Vi graver fortiden frem."