It bears the botanical name of chondrus crispus, and varies much in size and colour.
"Herbal Simples Approved for Modern Uses of Cure"
William Thomas Fernie
Among the most frequent of our sea-weeds, both as growing in the rock pools and cast ashore, is chondrus crispus, already twice referred to in connexion with its officinal uses.
"Sea-Weeds, Shells and Fossils"
Peter Gray B. B. Woodward