Knotted Wrack pustules

Knotted Wrack pustules

Observation - Knotted Wrack pustules - UK and Ireland. Description: As I was photographing the reticulated Flat Periwinkle (as you do!), I noticed the orange pustules on the usually warty reproductive bodies (conceptacles). They seem to coincide with the inner warts of the body. I would like to know if they are part of t

As I was photographing the reticulated Flat Periwinkle (as you do!), I noticed the orange pustules on the usually warty reproductive bodies (conceptacles). They seem to coincide with the inner warts of the body.
I would like to know if they are part of the reproductive process or, perhaps, a pathogen.