  Nebulae around symbiotic Miras look very much like genuine planetary nebulae,
although they are formed in a slightly different way. We present near infrared
photometry of known and suspected symbiotic nebulae obtained with the Deep Near
Infrared Southern Sky Survey (DENIS). We demonstrate that the near infrared
colours are an excellent tool to distinguish symbiotic from genuine planetary
nebulae. In particular we find that the bipolar planetary nebulae M 2-9 and Mz
3 are in fact symbiotic Miras. Further observations on prototype symbiotic
Miras prove that the proposed classification scheme works generally.
