Found at low tide at shoreline in rock pool. Noted that it was attached to a rock by a very slender stem.
No interactions present.
This is getting a little confused. The species doesn't seem to be F.serratus; the edge of the frond has no serrations. But the other algae around it indicate its growing in the low shore. F.spiralis is a high shore species. Confusingly, not all forms of F.vesiculosus have bladders and so that ID shouldn't be ruled out, particularly as this species extends downshore to the upper limits of F.serratus.
Lat/Lng: 56.081469, -3.159826
OS grid ref: NT279882