The hydroid colonies of this species are known as snail fur or eremittkrepshydroider because they often grow on snail shells inhabited by hermit crabs, giving the shell a furry appearance. These names are unfortunately a little misleading, since Hydractinia echinata is not the only hydractiniid that grows on hermit crab shells, and neither is it restricted to this substrate. A good sign to recognize this common shallow water species is the presence of large spines with ‘serrated’ (spiky) edges.
