Encrusting thing on Dilsea

Encrusting thing on Dilsea

Observation - Encrusting thing on Dilsea - UK and Ireland. Description: Found on a frond of, probably, Dilsea carnosa, Red Rags, in drift seaweeds. Identity of the substrate is not certain but I am fairly sure. Both sides of the frond had these pale patches, but in different patterns. I am assuming that these are no

Found on a frond of, probably, Dilsea carnosa, Red Rags, in drift seaweeds. Identity of the substrate is not certain but I am fairly sure. Both sides of the frond had these pale patches, but in different patterns. I am assuming that these are not part of the alga. The close up picture shows the 'lichen-like' appearance of the growth. I can't really decide if this is algal or animal, my only thought is that it may be a Lithothamnion relative???