A very common and conspicuous bryozoan throughout Britain and North America’s Pacific coast. Colonies form white or light grey encrusting sheets on algal substrates, with short tubercules or spines protruding from the zooids. Colonies can become very large, covering extensive areas of kelp fronds. Colonies are found from the lower intertidal down to the limit of the kelp forests
M. membranacea is recognised an invasive bryozoan species and can have serious ecological impacts on kelp forests.