The icon shows Large Magellanic Cloud,
a satellite galaxy of our Milky Way and a member of
the Local Group.
There's only one irregular galaxy in Messier's catalog: M82, and this one is a distorted disk galaxy. The distortion is due to gravitational interaction with its larger and more massive neighbor M81.
Another, very similar example is at least mentioned in Messier's catalog, though it did not get a number on its own: NGC 5195, the companion of the Whirlpool galaxy M51, which had been discovered by Pierre Mechain. The only further irregular galaxies known to 1782 are the Large and the Small Magellanic Cloud; these are probably miniature disk galaxies in mutual gravitational interaction, and in interaction with our Milky Way.
Last Modification: 25 Jan 1998, 16:10 MET