Nanaimo nudibranchs (Acanthodoris nanaimoensis) are very distinctive with their white colouration and maroon-tipped rhinophores (sensory organs) and gills. The amount of this maroon colouration can vary greatly between individuals. Very long papillae covering the oval body of this nudibranch give it a fuzzy appearance. Yellow tips to these papillae and a light yellow margin are also distinctive features. A dark colour phase may also be noticed that is brown or a brownish-grey. Nanaimo nudibranchs can grow to 1.5 inches (4cm) in length, with a range from central Alaska to southern California.