mystery holes

mystery holes

Observation - mystery holes. Description: Total mystery! These come in small groups around the Western Isles,along shore line. They also seen in Shetlands. 25-30mm in diameter. Depth varies. Side walls fairly smooth. Bottom roughish with a slightly deeper groove at 'outer' edge (Pic on right has

Total mystery! These come in small groups around the Western Isles,along shore line. They also seen in Shetlands. 25-30mm in diameter. Depth varies. Side walls fairly smooth. Bottom roughish with a slightly deeper groove at 'outer' edge (Pic on right has sand in it and gives idea of what I mean). They could be man made, but none of the older generation that I have spoken too, know anything about them. Any chance they are made by a marine 'animal' of some sort?