  Fossil groups are systems with one single central elliptical galaxy and an
unusual lack of luminous galaxies in the inner regions. The standard
explanation for the formation of these systems suggests that the lack of bright
galaxies is due to galactic cannibalism. In this study we show the results of
an optical and X-ray analysis of RX J1340.6+4018, the prototype fossil group.
The data indicates that RX J1340.6+4018 is similar to clusters in almost every
sense, dynamical mass, X-ray luminosity, M/L and luminosity function, except
for the lack of L* galaxies.
  There are claims in the literature that fossil systems have a lack of small
mass haloes, compared to predictions based on the LCDM scenario. The
observational data gathered on this and other fossil groups so far offer no
support to this idea.
  Analysis of the SN Ia/SN II ejecta ratio in the inner and outer regions shows
a marginally significant central dominance of SN Ia material. This suggests
that either the merger which originated the central galaxy was dry or the group
has been formed at early epochs, although better data are needed to confirm
this result.
