This classification requires detailed study of each nebula and more recent attempts have been made to allow quick classification of nebulae based purely on their appearance. WR nebulae frequently are ring-shaped in appearance, possibly spherical. Others are irregular, either disrupted shells or formed from clumpy ejection.
Examples of this type of nebula include NGC 6888, NGC 2359, and NGC 3199. Some WR nebulae have a prominent spiral structure, for example the Pinwheel nebula.