Cott described the decorator crabs as using "concealment afforded by masks of adventitious material", giving as example the great spider crab "Hyas araneus" of Britain "which disguises itself very perfectly". When "H. araneus" specimens were moved from an environment where all the crabs were camouflaged with short pieces of seaweed into different environments, all of them had redecorated themselves with local materials after one night. One was among corallines, and was covered with a dense bush of the hydrozoan "Sertularia abietina". Another was on small shells and gravel, and was decorated with those. A third was among the crinoid "Antedon rosaceus", and had broken off pieces of crinoid arms as decoration.