Coming back in from a small reef on one of the places I visit regularly, I suddenly notice this stone. I've never seen it before although I have fished there many, many times. The row of small holes are made with a chisel with the purpose of cleaving the rock in tow in order to use it in a building - most like a church.
The holes were probably made between 1150 and 1200 A.D. That day, my two greatest passions came together - flyfishing and archaeology!