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I think that you might be mistaken.
My experience only extends to triqueter but I suspect you might be interptreting the ridges on the worn-down, eroded, areas (outer walls) as being double. I don't think we can see double ridges, specially in that small ring area - right of centre. From what I see there appears to be a more triangular ('triqueter') appearance to the tubes.
I'd be interested in your response.
Inevitably, the name has changed!
Spirobranchus triqueter WoRMS
See my recent post here http://www.ispotnature.org/node/383397
Lat/Lng: 57.3145, -6.1082
OS grid ref: NG527323