Colonies of this species are thin and encrusting; they can grow to several centimeters across depending upon the availability of the algal substrate. Autozooids at the growing edge often have an iridescent sheen and become a deep brown as they get older. The autozooids are polygonal in shape measuring 0.5-0.8 x 0.2-0.4mm.
This species is distributed all around the coastline of the British Isles on the mid-shore and shallow sublittoral.
This species colonises a range of mid to lower shore algal species including Fucus serratus, Ascophyllum nosodum, Chondrus crispus and very rarely it has been observed on the shells of Littorina obtusata at Ballochmartin Bay, Cumbrae Island, Scotland.
One of the most distinctive features are the developing embryos, that grow as a cluster of 6 to 7 and are a whitish buff colour. The reproductive season for this species is during the summer months.