Iridea edulis.

Botanical name: 

(Either these two are the same, or they're still confounded. I couldn't find any botanical references to "Iridea edulis", though. -Henriette.)

Iridea edulis Bory. Algae.

"It is an unaccountable fact that this plant should have been long confounded with Rhodymenia palmata — the true Irish eatable Dulse. I have never seen I. edulis eaten, but Stackhouse tells us that in Cornwall it is sometimes eaten by fishermen, who crisp it over the fire."

Sturtevant's Edible Plants of the World, 1919, was edited by U. P. Hedrick.