Orkneyjar’s report here ow.ly/1eGbP – much clearer pics than “The Orcadian”.
As the only other NMRS for Damsay is a site the excavator thought to be a Norse castle but is now believed to have been a broch it is probable that the orthostats in one photo could relate to this. Though a short talk was given on preliminary Rising Tide findings beside these nowt has appeared in print or in the report, so from memory the Bay of Firth has in it likely chambered mounds and (one or more) stone circles
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though IMHO this is more like circles of stones e.g. kerbed cairns as many Orkney sites have been called locally "stone circles" - if there should really be a stone circle there it makes the Stenness ones survival more fortuitous than significant ;-) ]