  We report the detection of the extremely red object (ERO), HR 10 (I-K= 6.5,
z=1.44), at 4.9 and 6.1 microns (rest-frame) with ISOCAM, the mid-infrared
(MIR) camera onboard the Infrared Space Observatory (ISO). HR 10 is the first
ERO spectroscopically identified to be associated with an ultra-luminous IR
galaxy (ULIG) detected in the radio, MIR and sub-millimeter. The rest-frame
spectral energy distribution (SED) of HR 10 is amazingly similar to the one of
Arp 220, scaled by a factor 3.8+/-1.3. The corresponding 8-1000 microns
luminosity (~ 7x10^12 h70^{-2} Lsol) translates into a star formation rate of
about 1200 h70^{-2} Msol/yr if HR 10 is mostly powered by star formation. We
address the key issue of the origin of the powerful luminosity of HR 10, i.e.
starburst versus active galactic nucleus (AGN), by using the similarity with
its closeby clone, Arp 220.
